Information reproducing system, information recording medium, and information recording apparatus

ABSTRACT

A binarizing section generates binarized data from an image signal of a dot code on an information recording medium read by a code reading section. The binarizing section has a reference dot detection section, a dot area measuring section, a threshold value modifying section and a threshold value determining section. The reference dot detection section binarizes the image signal with a predetermined threshold value prior to generating binarized data to detect a reference dot from a binarized code image. The dot area measuring section measures the area of the reference dot detected by the reference dot detection section. The threshold value modifying section modifies the threshold value for binarization in such a manner that the area measured by the dot area measuring section approaches a predetermined target value. The threshold value determining section binarizes the image signal with the threshold value modified by the threshold value modifying section.

BACKGROUND OF THE INVENTION

The present invention relates to an information recording medium, suchas paper on which so-called multimedia information including audioinformation, such as speech and music, video information obtainable froma camera, video equipment and the like, digital code data obtainablefrom a personal computer, a word processor and the like has beenrecorded as a two-dimensional code pattern which can optically be read,an information recording apparatus for recording the two-dimensionalcode pattern on the information recording medium and informationreproduction system which optically reads the code pattern to reproduceoriginal multimedia information.

Hitherto, a variety of mediums including magnetic tapes and opticaldisks have been known as mediums for recording speech, music and thelike. However, even if a multiplicity of copies of the foregoing mediumsare manufactured, the somewhat costly unit price cannot be reduced.Moreover, an excessively large space is required to store the copies.What is worse, in a case where the medium, on which speech has beenrecorded must be sent to a remote person, labor and time takeswastefully even if it is mailed or directly transported. Also so-calledmultimedia information including video information obtainable fromcamera, video equipment and the like and digital code data obtainablefrom a personal computer, word processor and the like except audioinformation encounters similar problems.

To solve the above-mentioned problems, the applicant of the presentinvention has, in EP 0,670,555A1 (corresponding to U.S. Ser. No.08/407,018) disclosed a system for recording, on an informationrecording medium such as paper, multimedia information including atleast any one of audio information, video information and digital codedata as image information which can be facsimiled and which can becopied in a large quantity with a low cost, that is, in the form of atwo-dimensional code pattern formed by two-dimensionally disposing aplurality of dots serving as encoded information, and a system forreproducing the two-dimensional code pattern.

The two-dimensional code pattern disclosed above is formed as shown inFIG. 1. That is, FIGS. 1a-1c correspond to FIG. 16 of EP 0,670,555A1 andshows a dot code 170 (see FIG. 1a) serving as a two-dimensional codepattern. Area A of FIG. 1 is shown in FIG. 1B. The data format of thedot code 170 is structured such that one block 172 (see FIG. 1c)comprise a marker 174, a block address 176, an error detection and errorcorrection data 178 and a data area 180 in which actual data is set. Theblocks 172 are two-dimensionally arranged in the longitudinal andlateral directions to form a dot code 170.

FIG. 2 corresponds to FIG. 17 of EP 0,670,555A1 and shows the structureof an apparatus for reproducing multimedia information. The informationreproducing apparatus comprises a detection section 184 for reading adot code from a sheet 182 on which the dot code 170 is printed, a scanconversion section 186 which recognizes image data supplied from thedetection section 184 as a dot code to normalize image data above, abinarizing section 188 for binarizing multivalue data, a demodulatingsection 190, an adjustment section 192 for adjusting data row, a dataerror correction section 194 for correcting a read error when data isreproduced and a data error, a data separation section 196 forseparating data in accordance with the attitude of data, a decompressionprocessing section for decompressing data compressed to be adaptable tothe attitude of data, a display section or a reproducing section oranother input device.

In the detection section 184, the dot code 170 on the sheet 182 isirradiated with light emitted from a light source 198, and reflectedlight is allowed to pass through an image forming optical system 200having lenses and the like and a spatial filter 202 arranged to, forexample, remove moire and the like, and then supplied to an image pickupsection 204 arranged to convert optical information into an electricsignal and comprising, for example, a CCD or a CMD so as to be detectedas an image signal. The image signal is amplified by a preamplifier 206.The light source 198, image forming optical system 200, spatial filter202, image pickup section 204 and the preamplifier 206 are accommodatedin an external light insulating section 208 for insulating disturbancecaused by external light. The image signal amplified by the preamplifier206 is converted into digital information by an A/D conversion section210, and then supplied to the following scan conversion section 186.

Note that the image pickup section 204 is controlled by a image pickupsection control section 212. In an example case where an inter-line typeCCD is employed to serve as the image pickup section 204, the imagepickup section control section 212 transmits control signals including aV blank section for vertical synchronization, an image pickup devicereset pulse signal for resetting information charge, a charge transfergate pulse signal for transmitting charges stored in charge transferstorage sections arranged two-dimensionally, a horizontal chargetransfer CLK signal which is a transfer clock signal for a horizontalshift register for transferring a charge in the horizontal direction totransmit the same to the outside, a vertical charge transfer pulsesignal for transferring the plurality of vertical shift register chargesinto a vertical direction to transfer the same to the horizontal shiftregister and the like.

The image pickup section control section 212 supplies a light emissioncell control pulse to keep light emission timing of the light source 198in synchronization with the timing of the transmission of the signals.

Image data is read in a period from a V blank to another V blank in onefield. The light source 198 does not continuously emit light but itemits light pulses with synchronization in field units. To preventintroduction of clock noise into the output is when the pulse isemitted, timing is controlled in such a manner that exposure isperformed during the V blank period, that is, a period in which theimage charge is not transmitted. That is, the light emission cellcontrol pulse is a very thin digital clock pulse which is generatedinstantaneously and thus supplies great electric power to the powersource. Therefore, any contrivance is required to prevent unintentionalintroduction of noise into the analog image signal. Thus, the lightsource is caused to emit pulse light beams in the V blank period. As aresult, S/N can be improved. The plus light emission causing the time inwhich light is emitted to be shortened is significantly effective ineliminating influence of shake occurring when a manual scanningoperation is performed and out of focus caused from movement of theimage pickup section 204. As a result, a high speed scanning operationcan be performed.

In order to prevent deterioration in the S/N ratio because ofdisturbance, such as external light, in spite of existence of theexternal light insulating section 208 when, for example, the reproducingapparatus has been inclined, a pulse for resetting the image pickupdevice is transmitted immediately before the light source 198 emitslight in the V blank period to reset the signal of the image.Immediately after the signal has been reset, light is emitted, andimmediately after the light emission, image data is read.

The scan conversion section 186 will now be described. The scanconversion section 186 is a section which recognizes image data suppliedfrom the detection section 184 as a dot code so as to normalize the dotcode. The recognition and normalization are performed as follows:initially, image data supplied from the detection section 184 is storedin an image memory 214, and then image data above is read out andsupplied to a marker detection section 216. The marker detection section216 detects a marker of each block. A data arrangement directiondetection section 218 used the markers to detect rotation or inclinationor data arrangement direction. In accordance with a result of thedetection, an address control section 220 reads image data from theimage memory 214 to perform correction so as to supply image data to aninterpolating section 222. At this time, distortion of each lensoccurring in the image forming optical system 200 of the detectionsection 184 is corrected in accordance with information about theaberration of the lenses supplied from the correcting memory 224 so asto as well as correct the lenses. Then, the interpolating section 222subjects image data to an interpolating process so as to convert imagedata into an original dot code pattern.

An output from the interpolating section 222 is supplied to thebinarizing section 188. Since the dot code 170 is basically composed ofwhite and black patterns, that is, it is binary information, the dotcode 170 is binarized by the binarizing section 188. At this time, thebinarizing operation is appropriately performed while causing athreshold value determination circuit 226 to determine the thresholdvalue in consideration of an influence of disturbance and an influenceof the amplitude of the signal.

Since modulation has been performed when data has been recorded,demodulation of data is initially performed by the demodulating section190, and then demodulated data is supplied to the data row adjustmentsection 192.

The data row adjustment section 192 initially causes a block addressdetection section 228 to detect the block address of the two-dimensionalblock. Then, a block address error detection and correction section 230detects and corrects an error of the block address, and then an addresscontrol section 232, in block units, stores data in a data memorysection 234. Since data is stored in block units as described above,data can be stored efficiently even if intermediate data does not existor data is input afterwards.

Then, data read from the data memory section 234 is supplied to the dataerror correction section 194 so that data errors are corrected. Anoutput from the data error correction section 194 is branched into twosections one of which is, through an I/F 236, supplied to a personalcomputer, a word processor, an electronic notebook or the like. Theother output is supplied to the data separation section 196 so that datais divided into images, characters written by the hand, graphs,characters, line drawings and sound (two types of which is originalsound and synthesized sound).

The image corresponds to a natural image and is a multivalue image. Theimage is decompressed by a decompression processing section 238 tocorrespond to a compression method, for example, JPEG, and then data,which cannot be corrected, is interpolated by a data interpolatingcircuit 240.

Binary image information, such as characters written by the hand, graphsand the like, are decompressed by a decompression processing section 242to correspond to the compression method, for example, MR, MH or MMR, andthen data, which cannot be corrected, is interpolated by a datainterpolating circuit 244.

Characters and line drawings are, by a PDL (Page Description Language)processing section 246, converted into another pattern for display. Alsoline drawings and characters, which have been encoded and decompressedfor the code, are decompressed (for example, a Huffman coding,Lempel-Ziv coding or the like) by a decompression processing section 248corresponding to the compression method, and then supplied to the PDLprocessing section 246.

Outputs from the data interpolating circuits 240 and 244 and the PDLprocessing section 246 are, by a synthesizing or switch circuit 250,synthesized or selected, and then converted into an analog signal by aD/A conversion section 252 so as to be displayed on a display unit 254,such as a CRT (a TV monitor) or an FMD (Face Mounted Display). Note thatthe FMD is a glassestype monitor (handy monitor) to be mounted on theface of the user, and can be effectively used for, e.g., a virtualreality operation or looking at an image on a large frame in a narrowspace.

Speech information is decompressed by a decompression section 256 tocorrespond to the ADPCM coding or the like, and data, the error of whichcannot be corrected, is interpolated by a data interpolating circuit258. In a case of speech synthesis, a speech synthesizing section 260 issupplied with the code of the speech synthesis of synthesize speech fromthe code to transmit the speech. In a case where the code is compressedin the foregoing case, the decompression processing section 262 subjectsthe code to a decompression process, such as Huffman coding, Lempel-Zivcoding or the like, similarly to the characters and the line drawings,and then the speech synthesis is performed.

Outputs from the data interpolating circuit 258 and the speechsynthesizing section 260 are, by a synthesizing or switch circuit 264,synthesized or selected so as to be converted into an analog signal byD/A conversion section 266, and then transmitted to a speech output unit268, such as a loudspeaker, a headphone or the like.

Characters and line drawings are directly transmitted from the dataseparation section 196 to a page printer or a plotter 270 so as to beprinted on a paper sheet as characters of a word processor, or enabledto be transmitted to the plotter as a line drawing or a drawing.

As a matter of course, also the image can be printed by a video printeras well as being displayed on the CRT and the FMD, and moreover theimage can be photographed.

An image reproducing apparatus having the foregoing structure isarranged such that, for example, the detection section 184 and the scanconversion section 186 are accommodated in a pen-like case so as to beused as a reading section for optically reading the dot code 170 on thesheet 182; and the reading section is held by the hand to manually scanthe surface of the sheet 182 along the recorded dot code 170 so as toread the code.

A group including the inventor of the present invention has developed aformat which is capable of raising the recording density of dot codes ofthe foregoing type and has filed in U.S. Ser. No. 08/571,776(corresponding to EP 0,717,398 A3). The format of the dot code is, asshown in FIG. 3, structured such that predetermined matching patterndots 278 are disposed at predetermined positions with respect to themarker 174, for example, between markers adjacent in the firstdirection. Moreover, address dots 280 indicating the address of theblock is disposed at a predetermined position, for example, betweenmarkers adjacent in a second direction. Each of the matching patterndots 278 and the address dots 280 is composed of a dot having the samesize as that of the data dots 282 disposed in the data area 180. Thus,the dot code 170 structured as described above enables the direction ofthe arrangement and the true center of the marker 174 serving as areference point for reading the data dots 282 to be obtained by usingthe matching pattern dots 278 having a predetermined pattern. Therefore,the reference points for reading can easily and accurately be obtained.Thus, even if code patterns are recorded densely, the position of eachdata dot 282 can accurately be calculated so that original multimediainformation can reliably be reproduced.

As the binarizing section 188 for appropriately performing thebinarizing operation while causing threshold value determining circuit266 to determine the threshold value, a binarizing circuit of a typedisclosed in Jpn. Pat. Appln. KOKAI No. 59-61383 has been known. Theforegoing binarizing circuit is arranged to obtain the maximum andminimum value of digital data converted by an A/D converter, the maximumand minimum value being those in the previous frame. In accordance withthe obtained values, a threshold value is calculated and the obtainedresult of the calculation is used as the threshold value of the presentframe so as to perform the binarizing operation.

The above-mentioned system for reproducing the dot code 170 isconsiderably affected by direct reflection because of the short distancefrom the surface of the sheet 182 to the image pickup section 204. Thus,a video signal obtained from the image pickup section 204unintentionally includes noise. If the image pickup section 204 has adefective pixels, noise is generated. Noise of the foregoing typeresults in that the maximum and minimum values cannot accurately beobtained by the binarizing circuit. As a result, a binarizing operationusing an appropriate threshold value cannot be performed. Even if anappropriate value can be obtained, an optimum threshold value cannotalways be obtained from the maximum and minimum values attributable tothe state where dots are printed.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, an object of the present invention is toprovide an information reproducing system, an information recordingmedium and an image reproducing apparatus capable of accuratelyextracting maximum and minimum values even from a subject having noise,capable of performing a binarizing operation with an appropriatethreshold value regardless of a state where dots are printed so thatoriginal multimedia information is accurately reproduced.

According to a first aspect of the present invention, there is providedan information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein    -   the binarizing means includes:        -   reference dot detection means which binarizes the image            signal with a predetermined threshold value prior to            generating binarized data so as to detect a reference dot            from the binarized code image;        -   dot area measuring means for measuring the area of the            reference dot detected by the reference dot detection means;        -   threshold value modifying means for modifying the threshold            value in such a manner that the area measured by the dot            area measuring means approaches a predetermined target            value; and        -   threshold value determining means for binarizing the image            signal with the threshold value modified by the threshold            value modifying means.

According to a second aspect of the present invention, there is providedan information reproducing system comprising;

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   region dividing means for dividing the picked up screen                of the dot code into a plurality of regions;            -   characteristic amount extracting means for extracting                the characteristic amount for binarization in region                units divided by the region dividing means;            -   threshold value calculating means for calculating the                threshold value for binarization in accordance with the                characteristic amount extracted by the characteristic                amount extracting means; and            -   threshold value determining means for binarizing the                image signal with the threshold value calculated by the                threshold value calculating means.

According to a third aspect of the present invention, there is providedan information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   peak value detection means for detecting the maximum                value and the minimum value of the luminance from a                predetermined detection region;            -   code detection means for detecting whether or not a code                exists in the detection region;            -   minimum value replacing means for replacing the minimum                value in the detection region with the minimum value of                one of the previous field and frame in a case where the                code detection means does not detect a code; and            -   threshold value calculating means for calculating the                threshold value for binarization for the same region of                one of a next field and a next frame from the detected                maximum value and the detected or replaced minimum value                in accordance with a predetermined interior division                ratio.

According to a fourth aspect of the present invention, there is providedan information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   peak value detection means for detecting the maximum                value and the minimum value of the luminance from a                predetermined detection region;            -   code detection means for detecting whether or not a code                exists in the detection region;            -   minimum value replacing means for replacing the minimum                value in the detection region with the minimum value of                the adjacent detection region in a case where the code                detection means does not detect a code; and            -   threshold value calculating means for calculating the                threshold value for binarization for the same region of                one of a next field and a next frame from the detected                maximum value and the detected or replaced minimum value                in accordance with a predetermined interior division                ratio.

According to a fifth aspect of the present invention, there is providedan information recording medium for use in an information reproducingsystem having code reading means for reading a desired dot code from aninformation recording medium on which multimedia information includingat least any one of audio information, image information and digitalcode data has been recorded in the form of a dot code which canoptically be read; binarizing means for generating binarized data froman image signal corresponding to the dot code read by the code readingmeans; and information reproducing means for restoring binarized datagenerated by the binarizing means to original multimedia information toreproduce multimedia information, the information recording mediumcomprising:

-   -   data dots which correspond to the contents of multimedia        information and which can optically be read; and    -   a reference dot arranged to be detected by the binarizing means        and serving as a reference when the threshold value is modified        to allow the area of the detected dot to approach a        predetermined target value.

According to a sixth aspect of the present invention, there is providedan information recording medium for use in an information reproducingsystem having code reading means for reading a desired dot code from aninformation recording medium on which multimedia information includingat least any one of audio information, image information and digitalcode data has been recorded in the form of a dot code which canoptically be read; binarizing means for generating binarized data froman image signal corresponding to the dot code read by the code readingmeans; and information reproducing means for restoring binarized datagenerated by the binarizing means to original multimedia information toreproduce multimedia information, the information recording mediumcomprising:

-   -   data dots which correspond to the contents of multimedia        information and which can optically be read; and    -   a reference dot serving as a reference when the binarizing means        detects the maximum value and the minimum value of the image        signal level corresponding to the dot code, detects a dot from a        code data binarized by a threshold value calculated from the        maximum vale and the minimum value in accordance with a        predetermined interior division ratio and modifies the interior        division ratio in such a manner that area of the detected dot        approaches a predetermined target value.

According to a seventh aspect of the present invention, there isprovided an information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   reference dot recording means for recording at least two types        of reference dots having at least different areas of shapes;    -   reference dot reading means for reading the reference dots        recorded by the reference dot recording means to binarize the        read reference dots;    -   reference dot selection means for subjecting the area of each        reference dot read by the reference dot reading means and a        predetermined reference value to a comparison to select a        reference dot having the different smaller than a predetermined        threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the reference dot        selected by the reference dot selection means.

According to an eighth aspect of the present invention, there isprovided an information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   reference dot recording means for recording reference dots        having different recording densities;    -   reference dot reading means for reading the reference dots        recorded by the reference dot recording means to binarize the        read reference dots;    -   recording density adjustment means for subjecting the area of        each of the reference dots read by the reference dot reading        means and a predetermined reference value to a comparison to        adjust the recording density in such a manner that the        difference is smaller than a predetermined threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the recording density        adjusted by the recording density adjustment means.

According to a ninth aspect of the present invention, there is providedan information recording apparatus for recording multimedia informationincluding at least any one of audio information, image information anddigital code data in the form of a dot code which can optically be read,comprising:

-   -   reference dot recording means for recording at least two or more        types of reference dots having different recording densities;    -   reference dot reading means for dividing a picked up screen in        such a manner that only one reference dot recorded by the        reference dot recording means is included in a divided region        and binarizing each divided region to read the reference dot to        binarize the reference dot;    -   density selection means for subjecting the area of each        reference dot read by the reference dot reading means and a        predetermined reference value to a comparison and for selecting        the density of the reference dot having the difference smaller        than a predetermined threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the recording density        selected by the density selection means.

According to a tenth aspect of the present invention, there is providedan information recording apparatus for recording multimedia informationincluding at least any one of audio information, image information anddigital code data in the form of a dot code which can optically be read,comprising:

-   -   input means for inputting information relating to the        information recording medium;    -   storage means for storing the relationship between information        relating to a predetermined information recording medium and one        of the area of the dot when data is recorded and the recording        density; and    -   means for reading corresponding one of the dot area and the        recording density from the storage means in accordance with        information input by the input means and relating to the        information recording medium so as to record a dot code        corresponding to multimedia information in accordance with the        one of the dot area and the recording density.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments, given below,serve to explain the principles of the invention.

FIGS. 1A-1C are diagrams showing a conventional two-dimensional dot codepattern;

FIG. 2 is a block diagram showing a conventional information reproducingapparatus;

FIG. 3 is a diagram showing another form of the dot code which is aconventional two-dimensional code pattern;

FIG. 4A is a block diagram showing a first embodiment of an informationreproducing system according to the present invention;

FIG. 4B is a block diagram showing a binarizing section according to afirst embodiment of the information reproducing system according to thepresent invention;

FIG. 5 is a diagram showing the area of a dot;

FIG. 6A is a block diagram showing a second embodiment of an informationreproducing system according to the present invention;

FIG. 6B is a flow chart showing the second embodiment of the informationreproducing system according to the present invention;

FIG. 7 is a block diagram showing another structure of the secondembodiment of the information reproducing system according to thepresent invention;

FIG. 8 is a flow chart showing the operation of the structure shown inFIG. 7;

FIG. 9A is a block diagram showing a third embodiment of an informationreproducing system according to the present invention;

FIG. 9B is a flow chart showing the third embodiment of the informationreproducing system according to the present invention;

FIGS. 10A and 10B are diagrams showing dot codes for use in a fourthembodiment of the information reproducing system according to thepresent invention and as well as in a first embodiment of an informationrecording medium according to the present invention;

FIGS. 11A and 11B are diagrams respectively showing examples of otherdot codes to be recorded on an information reproducing medium accordingto a first embodiment of the present invention;

FIG. 12 is a diagram showing a dot code for use in a fifth embodiment ofthe information reproducing system according to the present invention;

FIG. 13 is a block diagram showing a fifth embodiment of an informationreproducing system according to the present invention;

FIG. 14 is a diagram for explaining reading points;

FIG. 15 is an enlarged view of a peripheral portion of a data dotobtained by picking up an image of a data code by a CCD and bybinarizing the data code;

FIG. 16 is a diagram for explaining another method of calculating thecentroid;

FIG. 17 shows another example of the dot code for use in a fifthembodiment of the information reproducing system according to thepresent invention;

FIG. 18 is a block diagram showing a sixth embodiment of an informationreproducing system according to the present invention;

FIG. 19 is a diagram showing a dot code for use in a sixth embodiment ofthe information reproducing system according to the present invention;

FIG. 20 is a block diagram showing a seventh embodiment of aninformation reproducing system according to the present invention;

FIG. 21 is a block diagram showing an eighth embodiment of aninformation reproducing system according to the present invention;

FIG. 22 is a flow chart showing the operation of the informationreproducing system according to an eight embodiment of the presentinvention;

FIGS. 23A-23C are diagrams showing the relationship between first andsecond threshold values;

FIG. 24 is a diagram showing a method of calculating an average area;

FIG. 25 is a block diagram showing a ninth embodiment of an informationreproducing system according to the present invention;

FIG. 26 is a flow chart showing the operation of the informationreproducing system according to a ninth embodiment of the presentinvention;

FIG. 27 is a block diagram showing a tenth embodiment of an informationreproducing system according to the present invention;

FIG. 28 is a flow chart showing the operation of the informationreproducing system according to a tenth embodiment of the presentinvention;

FIG. 29 is a flow chart showing another example of the operation of theinformation reproducing system according to the tenth embodiment of thepresent invention;

FIG. 30 is a diagram showing the operation of an eleventh embodiment ofthe information reproducing system according to the present invention;

FIG. 31 is a diagram showing a frame obtained in a case where a dot codehas been scanned by a handy scanner;

FIG. 32 is a block diagram showing an eleventh embodiment of aninformation reproducing system according to the present invention;

FIG. 33 is a flow chart for, by a software manner, realizing theeleventh embodiment of the information reproducing system according tothe present invention;

FIG. 34 is a block diagram showing a twelfth embodiment of aninformation reproducing system according to the present invention;

FIG. 35 is a flow chart showing the operation of the informationreproducing system according to the twelfth embodiment of the presentinvention;

FIG. 36A is a diagram showing the structure of a thirteenth embodimentof the information reproducing system according to the presentinvention;

FIG. 36B is a table showing contents stored in an interior divisionratio modification table according to a thirteenth embodiment of theinformation reproducing system according to the present invention;

FIG. 37 is a graph explaining the operation of a fourteenth embodimentof the information reproducing system according to the present inventionand showing the relationship between the areas of a dot and the interiordivision ratios;

FIG. 38 is a graph explaining the operation of a fifteenth embodiment ofthe information reproducing system according to the present inventionand showing the relationship between the areas of a dot and the interiordivision ratios;

FIG. 39 is a flow chart showing the operation of the informationreproducing system according to the fifteenth embodiment of the presentinvention;

FIG. 40 is a graph showing the relationship between calculated interiordivision ratios and actual values for explaining the operation of asixteenth embodiment of the information reproducing system according tothe present invention;

FIG. 41 is a graph explaining the operation of a seventeenth embodimentof the information reproducing system according to the present inventionand showing the relationship between the areas of a dot and the interiordivision ratios;

FIG. 42 is a block diagram showing a seventeenth embodiment of aninformation reproducing system according to the present invention;

FIG. 43 is a flow chart showing the operation of the informationreproducing system according to the seventeenth embodiment of thepresent invention;

FIG. 44 is a block diagram showing an eighteenth embodiment of aninformation reproducing system according to the present invention;

FIG. 45 is a flow chart showing the operation of the informationreproducing system according to the eighteenth embodiment of the presentinvention;

FIG. 46 is a flow chart showing the operation of the informationreproducing system according to a nineteenth embodiment of the presentinvention;

FIG. 47 is a diagram showing a dot code for use in a twentiethembodiment of the information reproducing system according to thepresent invention;

FIG. 48 is a block diagram showing a twentieth embodiment of aninformation reproducing system according to the present invention;

FIG. 49 is a diagram showing a shaded image for explaining atwenty-first embodiment of the information reproducing system accordingto the present invention;

FIG. 50 is a block diagram showing a twenty-first embodiment of aninformation reproducing system according to the present invention;

FIG. 51 is a diagram showing a dot code for use in a twenty-secondembodiment of the information reproducing system according to thepresent invention;

FIG. 52 is a diagram showing a dot code for use in a twenty-thirdembodiment of the information reproducing system according to thepresent invention;

FIG. 53A is a diagram showing a shaded code image for explaining atwenty-fourth embodiment of the information reproducing system accordingto the present invention;

FIG. 53B is a diagram showing the maximum luminance and the thresholdvalue for each of divided regions;

FIG. 54A is a diagram showing a shaded code image for explaining atwenty-fifth embodiment of the information reproducing system accordingto the present invention;

FIG. 54B is a diagram showing a state where the minimum luminance of theoverall frame is applied to the minimum value for each of the dividedregions in the twenty-fifth embodiment of the information reproducingsystem according to the present invention;

FIG. 55 is a diagram showing a state where the minimum luminance of theoverall body of the previous frame is applied to the minimum value foreach of the divided regions of the present frame in the twenty-sixthembodiment of the information reproducing system according to thepresent invention;

FIG. 56A is a diagram showing a state of a change of shading betweenframes according to a twenty-seventh embodiment of the informationreproducing system according to the present invention;

FIG. 56B is a diagram showing a state of transition of the irregularityof the ground color between frames;

FIG. 57 is a block diagram showing a twenty-seventh embodiment of aninformation reproducing system according to the present invention;

FIG. 58 is a diagram showing a state where the ground color is graduallybrightened as the time passes in a certain divided region of a picked upimage and an image which has been binarized for explaining atwenty-eighth embodiment of the information reproducing system accordingto the present invention;

FIG. 59 is a block diagram showing a twenty-eighth embodiment of aninformation reproducing system according to the present invention;

FIG. 60 is a diagram showing the operation of a twenty-ninth embodimentof the information reproducing system according to the presentinvention;

FIG. 61 is a flow chart showing the operation of the informationreproducing system according to a thirtieth embodiment of the presentinvention;

FIG. 62 is a flow chart of a process for calculating the interiordivision ratio according to the thirty-first embodiment of the presentinvention;

FIG. 63 is a flow chart of a process for calculating the threshold valuein a thirty-first embodiment of the information reproducing systemaccording to the present invention;

FIG. 64 is a flow chart of a binarizing process according to thethirty-first embodiment of the information reproducing system accordingto the present invention;

FIG. 65 is a block diagram showing a thirty-first embodiment of aninformation reproducing system according to the present invention;

FIGS. 66A and 66B are diagrams showing the flow of a process in thethirty-first embodiment of the information reproducing system accordingto the present invention;

FIG. 67 is a timing chart for explaining a two-system independentcontrol of the interior division ratio;

FIGS. 68A and 68B are diagrams respectively showing dot codes recordedon an information recording medium according to a third embodiment ofthe present invention;

FIGS. 69A and 69B are diagrams respectively showing dot codes recordedon an information recording medium according to a fourth embodiment ofthe present invention;

FIGS. 70A and 70B are diagrams respectively showing dot codes recordedon an information recording medium according to a fifth embodiment ofthe present invention;

FIG. 71A is a diagram showing reference dots to be printed before anactual dot code is printed by an information reproducing apparatusaccording to a first embodiment the present invention;

FIG. 71B is a diagram showing the contrast between the area of thereference dots shown in FIG. 71A and a reference value;

FIG. 72 is a block diagram showing a first embodiment of an informationrecording apparatus according to the present invention;

FIG. 73 is a flow chart showing the operation of the informationrecording apparatus according to the first embodiment of the presentinvention;

FIG. 74 is a diagram showing the operation of a second embodiment of theinformation recording apparatus according to the present invention;

FIG. 75A is a diagram showing the difference in the density between thebackground region and a reference dot according to a third embodiment ofthe information recording apparatus according to the present invention;

FIG. 75B is a diagram showing reference dots to be printed before anactual dot code is printed by an information recording apparatusaccording to a third embodiment of the present invention;

FIG. 75C is a diagram showing the contrast between the area of thereference dot shown in FIG. 71A and a reference value;

FIG. 76 is a block diagram showing a third embodiment of an informationrecording apparatus according to the present invention;

FIG. 77 is a flow chart showing the operation of the informationrecording apparatus according to the third embodiment of the presentinvention;

FIG. 78A is diagram showing reference dots to be printed before anactual dot code is printed by an information recording apparatusaccording to a fourth embodiment of the present invention;

FIG. 78B is a diagram showing the contrast between the areas of thereference dots shown in FIG. 78A and a reference value;

FIG. 79 is a block diagram showing a fourth embodiment of an informationrecording apparatus according to the present invention;

FIG. 80 is a flow chart showing the operation of the informationrecording apparatus according to the fourth embodiment of the presentinvention; and

FIG. 81 is a block diagram showing a fifth embodiment of an informationrecording apparatus according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described withreference to the drawings.

Note that same structures, functions and processes among the followingembodiments are given the same reference numerals.

Initially, an information reproducing system will now be described.

FIG. 4A is a diagram showing the structure of a first embodiment of theinformation reproducing system according to the present invention. Acode reading section 10 reads a required dot code from an informationrecording medium 12 in which multimedia information including at leastaudio information, image information and digital code data is recordedin the form of a dot code which can optically be read. The code readingsection 10 corresponds to the detection section 184 and the scanconversion section 186 disclosed in, for example, EP 0,670,555 A1. Abinarizing section 14 generates binarized data from a image signalcorresponding to the dot code read by the code reading section 10. Thebinarizing section 14 corresponding to the binarizing section 188 andthe threshold value determination circuit 226 disclosed in EP 0,670,555A1. An information reproducing section 16 restores and reproducesbinarized data generated by the binarizing section 14 to originalmultimedia information. The information reproducing section 16corresponding to elements ensuing the demodulating section 190 disclosedin EP 0,670,555 A1.

The binarizing section 14 according to the first embodiment, as shown inFIG. 4B, comprises, a reference dot detection section 14A, a dot areameasuring section 14B, a threshold value modifying section 14C and athreshold value determining section 14D. The reference dot detectionsection 14A threshold value determining section 14D, prior to generatingbinarized data to be supplied to the information reproducing section 16,binarizes an image signal supplied from the code reading section 10 witha predetermined threshold value, and then the reference dot detectionsection 14A detects a reference dot from the binarized code information.As the reference dot to be described later, for example, a pattern dot278 may be employed. The dot area measuring section 14B measures thearea of the reference dot detected by a reference dot detection section14A. The threshold value modifying section 14C modifies the thresholdvalue for use in the binarizing process in such a manner that the areameasured by the dot area measuring section 14B approaches apredetermined target value. The threshold value determining section 14Dbinarizes the image signal with the threshold value modified by thethreshold value modifying section 14C, and then transmits the obtainedbinarized data to the information reproducing section 16.

That is, in the foregoing structure, the picked up reference dot isbinarized with appropriate threshold value TH, as shown in FIG. 5. Inthis case, since change in the luminance as shown in FIG. 5 is obtainedwhen a dot image has been picked up, the change is cut by a plane of anappropriate threshold value TH so that the cross sectional is obtainedas dot area S. If the dot area S is larger than a predetermined targetvalue, the threshold value of the luminance is modified to a smallervalue so that threshold value plane TF′ is obtained. As a result, thedot area S′, which is a cross section obtained by cutting the luminancewith the threshold value plane TH′, can be reduced. If the dot area S issmaller than the target value, the threshold value is modified to alarger value so that a larger dot area is obtained.

As described above, the structure in which the threshold value ismodified by using the dot area enables a binarizing process to beperformed with a required dot size without dependency upon the expansionand contraction of the dot attributable to the recording state.

Even if the dot has anisotropy (if the dot is not in the form of acircle, but it is, for example, an ellipse), or if the dot haswhisker-like noise or stain, the binarizing process can accurately beperformed.

A second embodiment of the information reproducing system according tothe present invention will now be described.

In the second embodiment, the binarizing section 14 performs the processfor binarizing an image signal read by the code reading section 10 infield or frame units.

That is, as shown in FIGS. 6A and 6B, the threshold value determiningsection 14D binarizes frame image data with an appropriate thresholdvalue, the reference dot detection section 14A detects a reference dot,and the dot area measuring section 14B measures the area of the dot.Then, the threshold value modifying section 14C uses the area to modifythe threshold value, and the threshold value determining section 14Dbinarizes image data in the same frame with the foregoing thresholdvalue.

Since the threshold value of the same code image with which thereference dot area has been measured is modified to again perform thebinarizing process, the binarizing process can be performed in such amanner that the dot area can accurately be adapted to a target value.

A structure shown in FIG. 7 may be employed. That is, a comparator 14Eis provided to subject the dot area measured by the dot area measuringsection 14B and a target value to a comparison. Then, the thresholdvalue is modified by the threshold value modifying section 14C until thedifference is made to be within a predetermined range. If the differencehas been made to be within the predetermined range, binarized datatransmitted from the threshold value determining section 14D is suppliedto the following information reproducing section 16.

That is, as shown in FIG. 8, an appropriate threshold value th is usedto binarize image data, and a reference dot is detected, and then itsarea S is calculated (step S11). Then, an absolute value of thedifference between the calculated area S and target area S_(t) isobtained and the obtained absolute value is compared with apredetermined threshold value TH (step S12). If the absolute value ofthe difference is larger than the threshold value TH, whether thecalculated area S is smaller than the target area S_(t) is determined(step S13). If the area S is smaller than the target area S_(t), thethreshold value th for the binarizing process is enlarged by apredetermined amount Δth (step S14). If the area S is larger than thetarget area S_(t), the threshold value th is reduced by thepredetermined amount Δth (step S15), and then the operation returns tostep S11. The above-mentioned process is repeated until the absolutevalue of the difference from the target area S_(t) is made to be smallerthan the threshold value TH. When the absolute value of the differencebetween the area S and the target area S_(t) is made to be smaller thanthe threshold value TH, a result of the binarizing process obtained byusing the threshold value th is transmitted (step S16).

As described above, the modification and the binarization of thethreshold value are performed repeatedly until the measured dot areaapproaches the target value. When the dot area has satisfactorilyapproached the target value, the binarized data at this time istransmitted. Therefore, the binarizing process can be performed in sucha manner that the dot area can accurately be adapted to the targetvalue.

A third embodiment of the information reproducing system according tothe present invention will now be described.

In a case when the image of the dot code 170 is continuously picked up,the illumination state and recording state are not changed considerablyamong continuous frames. The third embodiment is structured by using thecharacteristic that the threshold value of the present frame can bedetermined by using the state of the previously frame.

That is, as shown in FIGS. 9A and 9B, the threshold value determiningsection 14D binarizes an image signal of the present frame with anappropriate threshold value for the binarizing process, the referencedot detection section 14A detects the reference dot in accordance with aresult of the binarizing process, and then the dot area measuringsection 14B measures the dot area. Then, the threshold value modifyingsection 14C uses the measured dot area to modify the threshold value,and the modified threshold value is stored by the threshold valuestorage section 14F so as to be used when an image signal of the nextframe is binarized.

As described above, the code reading section 10 continuously reads thedot code images, and the binarizing section 14 modifies the thresholdvalues of the read and continuous image signals from the previous fieldor the previous frame in accordance with the detected area of thereference dot so as to binarize the present field or the present frameby using the modified threshold values. Therefore, in a case where thecode images are successively read over a plurality of frames, thequantity of light and the recording conditions are not changedconsiderably and, therefore, the threshold value of the previous frame.Thus, a memory for storing images can be omitted and a real time processcan be performed.

A fourth embodiment of the information reproducing system according tothe present invention will now be described.

In a case where a reference dot, which cannot reliably be detected, or areference dot having a stable area and thus having poor correlation withthe data dots 282 has been selected, the data dots 282 cannot easily beallow to approach a required size. Accordingly, this embodiment uses thedata dots 282 or an isolated dot recorded similarly to that of the datadots 282, for example, an isolated dot having substantially the samesize and the same shape as those of the data dots 282.

For example, an isolated dot among data dots is searched to be used asthe reference dot 18, as shown in FIG. 10A.

As an alternative to this, as shown in FIG. 10B, a region for areference dot is provided in another region for the data dots 282 so asto record an isolated dot in the provided region so as to be used as thereference dot 18.

That is, a dot recorded in a state similar to that of the data dots 282is used as the reference dot 18 so that the data dots 282 can reliablybe allowed to approach a target area.

That is, since the isolated dot does not interfere with another dot, thearea can accurately be measured and the recording state approximates thedata dots 282 which must be read. By using the binarizing state of thereference dot 18 as a reference for determining whether the binarizingstate is acceptable, an optimum binarizing state can be realized.

The reference dot 18 may be disposed on the code at the leading end ofthe same as shown in FIG. 11A, or the same may be repeated atintermediate positions of the code, as shown in FIG. 11B.

A fifth embodiment of the information reproducing system according tothe present invention will now be described.

According to the fifth embodiment, the dot code 170 recorded on theinformation recording medium 12 comprises a data code 20 correspondingto multimedia information and a pattern code 22 for determining aposition at which the data code 20 is read. Moreover, at least a portionof the pattern code 22 is used as the reference dot 18. The pattern code22 has been described in detail in U.S. Ser. No. 08/571,776(corresponding to EP 0,717,398 A3) filed by the applicant of the presentinvention.

Specifically, the pattern dot 278 in the pattern code can be used as thereference dot 18, as shown in FIG. 12.

That is, data dots 282 in the data code 20 have centers disposed in alattice configuration. To decrease reading errors, the reading pointsmust accurately be aligned to the lattice points. Accordingly, the codereading section 10 having the structure as shown in FIG. 13 uses thepattern dots 278 in the pattern code 22 to accurately determine thereading points.

That is, a marker detection section 24 detects the marker 174, and amarker center calculating section 26 calculates the centroid of themarker 174. Since the calculated specific centroid is, at this time,unsatisfactory in a viewpoint of accuracy to serve as a reference pointfor reading data dots recorded densely, it is called a “substantialcenter”. To improve the accuracy, a pattern dot detection section 28detects the pattern dots 278 from the above-mentioned substantial centerin accordance with a known code format. The centroids of the patterndots 278 are calculated by a dot center calculating section 30. By usingdistribution of the positions of the centroids, the reading referencepoint calculating section 32 calculates reading reference points. Thereading reference points exhibit satisfactory accuracy because the errorin each centroid can be averaged by the number of the pattern dots.Therefore, the reading reference point is called a true center. Then, areading point calculating section 34 equally divides the distancebetween the thus-obtained true centers in accordance with the codeformat as shown in FIG. 14 to obtain reading points so as to read thedata dots 282.

FIG. 15 is an enlarged view of a peripheral portion of the data dot 282obtained when the image of the data code 20 has been picked up by a CCDand then it has been binarized. On the surface of the CCD, a dotrecorded densely cannot be picked up in the form of a circular shape andblack pixels are formed in only regions in which the dots overlap theCCD pixels by half or greater. Therefore, to decrease reading errors,the portion in the vicinity of the center of the dot, on which the stateof the dot is reflected must be read. Thus, the foregoing process isrequired. The processes to be performed by respective processingsections may be those disclosed in, for example, U.S. Ser. No.08/571,776 corresponding to EP 0,717,398 A3.

The marker center calculating section 26 and the dot center calculatingsection 30 are able to calculate the centroid by dividing the total sumof coordinates of black pixels forming the dot by the total sum of theblack pixels, that is, the area of the dot as shown in FIG. 16.

As described above, since the pattern dot 278, which is a portion of thepattern code 22, is an isolated dot having substantially the same sizeand the same shape as those of the data dots 282 and the code readingsection 10 calculates its area for detecting the centroid in order todetermine the reading positions, the process to be performed by thereference dot detection section 14A and that to be performed by thethreshold area measuring section 14B can be made to be a common process.Therefore, the efficiency can be improved.

As an alternative to this, the marker 174 in the pattern code may beused as the reference dot 18, as shown in FIG. 17.

That is, since the marker 174, which is a portion of the pattern code22, is detected in an initial stage of the reading process and its areahas been calculated to detect the centroid for determining the position,use of a result of the calculation enables the process to be performedefficiently.

A sixth embodiment of the information reproducing system according tothe present invention will now be described.

In the sixth embodiment, the dot area measuring section 14B is, as shownin FIG. 18, composed of a dot interval measuring circuit 14B1, a dotarea measuring circuit 14B2 and a dot area correction circuit 14B3. Thedot interval measuring circuit 14B1 measures the distance betweenpredetermined dots forming the pattern code 22, for example, thatbetween markers. The dot area measuring circuit 14B2 measures the areaof the pattern dots 278 forming the pattern code 22 which is thereference dot 18. The dot area correction circuit 14B3 corrects the areaor the target value of the reference dot 18 measured by the dot areameasuring circuit 14B2 in accordance with the interval between dotsmeasured by the dot interval measuring circuit 14B1.

That is, as shown in FIG. 19, a pair of markers is detected as intervalmeasuring dots 38, the interval between which must be measured, tocalculate distance 1 between the markers. Since a plurality of pairs ofmarkers can be searched usually in one image pickup area (a frame), anaverage distance between markers obtainable by calculating the averagevalue is used as reference dot interval L. Assuming that the area beforethe correction is S, corrected area S′ can be obtained, for example, asfollows: $S^{\prime} = {\left( \frac{l}{L} \right)^{2}S}$

As described above, the distance between dots in a code having apredetermined positional relationship is measured. Then, in accordancewith the measured distance, at least either of the area of the referencedot 18 or the target value of the same is corrected so that change inthe dot area occurring due to upward or downward movement or distortionof the camera is corrected. As a result, the area can stably bemeasured.

Moreover, even if the magnification of the optical system is changed, arequired operation can be performed. Moreover, a code (for example, 50μm or 60 μm) printed at a different printing magnification can be read.

A seventh embodiment of the information reproducing system according tothe present invention will now be described.

The seventh embodiment is arranged such that the reference dot detectionsection 14A detects a plurality of reference dots 18 and the dot areameasuring section 14B calculates the average area of the detected pluralreference dots 18.

That is, as shown in FIG. 20, a dot area measuring circuit 14B4 measuresthe area of each reference dot 18, a dot counting circuit 14B5 countsthe number of the reference dots 18, the area of each of which has beenmeasured, and an average area calculating circuit 14B6 divides the totalsum of the areas of the reference dots 18 by the number of the referencedots 18 to calculate the average dot area.

In a case where the reference dot 18 is sampled by plural pixels in thelongitudinal and lateral directions, the area of the reference dot 18cannot stably be calculated because of the relative position of thereference dot 18 with respect to the pixel and noise. Therefore, thearea, which is used as the reference of the binarizing process, cannotstably be calculated. Accordingly, the seventh embodiment has astructure such that a plurality of reference dots 18 are previouslyrecorded, and then the reference dots 18 are detected. Then, a processfor averaging the plural reference dots 18 is performed to improve thereliability. That is, the average area of the plural reference dots 18is calculated so that influence of change in the area and noiseoccurring due to the positional relationship can be set off. Thus, thearea can further accurately be calculated.

An eighth embodiment of the information reproducing system according tothe present invention will now be described.

In addition to the structure according to the seventh embodiment, theeighth embodiment has an additional structure arranged such that thearea of sum reference dot 18 is excluded from the calculation forobtaining the average area if the measured area of the some referencedot 18 is larger than a predetermined range.

As shown in FIG. 21, a dot selection section 14B7 is provided to causethe dot counting circuit 14B5 to perform the counting operation and theaverage area calculating circuit 14B6 to perform the average areacalculating operation only when the area of the reference dot 18measured by the dot area measuring circuit 14B4 is included in apredetermined range.

As shown in FIG. 22, registers SS and S_(num) are initialized to “0”(step S21), and then whether or not detection has been completed isdetermined (step S22). If detection has not been completed, area S ofthe i-th reference dot 18 is calculated by the dot area measuringcircuit 14B4 (step S23). Then, the dot selection section 14B7 determineswhether or not the calculated area S_(i) is included in a predeterminedrange, that is, from first threshold value TH₁ and second thresholdvalue TH₂ (step S24). Note that assumptions are performed that TH₁ andTH₂ hold a relationship as TH₁<TH₂, as shown in FIG. 23.

If the calculated area S is not included in the foregoing range, adetermination is performed that the calculated area S is a dot areacalculated erroneously attributable to a stain or blurring. Thus, thearea S is deleted, and then the operation returns to step S22 so thatthe operation proceeds to process a next reference dot 18.

If the calculated area S_(i) is included in the foregoing range, thecalculated area S is added to the value of the register SS, and thevalue of the register S^(num) calculated by the dot counting circuit14B5 is increased (step S25), and then the operation returns to stepS22.

After detection has been completed, the average area calculating circuit14B6 divides the value of the register SS by the value of the registerS_(num) so that average area S_(avg) is calculated (step S26).

If dot area S₄ is thickened attributable to blurring and dot area S₇ isthinned attributable to patchy portion, the area S₄ is larger thansecond threshold value TH₂ and the area S₇ is smaller than firstthreshold value TH₁. Therefore, the dot selection section 14B7 rejectsthe foregoing areas from calculation of the average area. Therefore, thenumber of dots which is counted by the dot counting circuit 14B5 is six,that is, S₁, S₂, S₃, S₅, S₆ and S₈. The average area to be calculated bythe average area calculating circuit 14B6 is the average of the sixareas.

By excluding the dot areas calculated erroneously attributable to astain, a patchy portion or blurring as described above, the average areacan stably be calculated.

A ninth embodiment of the information reproducing system according tothe present invention will now be described.

The reference dot 18 cannot correctly be detected attributable to noiseor the like in an inappropriate printing state or image pickup state. Ifthe threshold value is modified to correspond to the reference dot 18detected in the foregoing state, an inappropriate threshold value isset. The reference dot 18 cannot be detected from an image binarizedwith the inappropriate threshold value and restoration to a normalthreshold value is sometime inhibited.

Accordingly, the ninth embodiment has a structure such that modificationof the threshold value with the reference dot area is not performed ifthe reference dots 18 satisfying the conditions cannot be detected by anumber not less than a predetermined number.

As shown in FIGS. 25 and 26, the threshold value modifying section 14Csupplies, to a threshold value modification selection circuit 14C1aforming a threshold value holding section 14C1, the total sum S_(num) ofthe reference dots 18 counted by the dot counting circuit 14B5 of thedot area measuring section 14B to determine whether the total sumS_(num) is larger than third threshold value TH₃ (step S31). If thetotal sum S_(num) is not larger than the third threshold value TH₃, theoperation for modifying the threshold value which is performed by thethreshold value modifying circuit 14C2 is not performed but thresholdvalue th stored in a threshold value stored circuit 14C1b is transmitted(step S32). If the detected total sum S_(num) is larger than the thirdthreshold value TH₃, the threshold value modifying circuit 14C2 performsthe threshold value modifying operation (+Δth) so as to transmitmodified threshold value th (step S33).

If the reference dots 18 are twelve pattern dots 278 disposed betweenmarkers and is six blocks 272 are placed in one image pickup area (aframe), 96 reference dots are detected. When scanning is started, theimage pickup operation starts in a state where the dot code 170 issubstantially introduced into the image pickup area. Thus, there is arisk that the modification of the threshold value starts at anunsatisfactory reference dot 18. Accordingly, it is preferable that thethird threshold value TH₃ be dots for about two blocks, that is, about48 (12×4) dots. However, lack of one or two dots sometimes takes placefor some reason or other, dots by a number larger than 40 are detectedin this embodiment.

As described above, by employing the structure such that the thresholdvalue is not modified if the satisfactory number of reference dots 18cannot be detected, the reliability of the threshold value can bemaintained. That is, since the image of the block 272 cannotsatisfactorily be picked up when scanning is started, modification ofthe threshold value in the foregoing state sometimes deteriorates theresult. Thus, modification of the threshold value is inhibited in theforegoing case so as to maintain the reliability.

A tenth embodiment of the information reproducing system according tothe present invention will now be described.

According to the tenth embodiment, the threshold value modifying section14C comprises a peak value detection section 14C3, an interior divisionratio modification section 14C4 and a threshold value calculationsection 14C5, as shown in FIG. 27. The peak value detection section 14C3detects the maximum and minimum values of the luminance from apredetermined region to be detected. The interior division ratiomodification section 14C4 modifies the interior division ratio inaccordance with the amount of modification of the interior divisionratio calculated from the difference between the area measured by thedot area measuring section 14B and a predetermined target value. Thethreshold value calculation section 14C5 divides the value detected bythe peak value detection section 14C3 by the interior division ratiomodified by the interior division ratio modification section 14C4 so asto calculate the threshold value.

With the foregoing structure, the peak value detection section 14C3, asshown in FIG. 28, detects, from image data, maximum value max andminimum value min which are peak values (step S41). The threshold valuecalculating section 14C5 interiorly divides the peak values by interiordivision ratio k so as to calculate the threshold value th (step S42).That is, the threshold value th can be calculated as follows:tk=k(max−min)+min   (1)Note that the interior division ratio k is a ratio modified and storedby the interior division ratio modification section 14C4 as describedlater.

Thus, the reference dot 18 binarized by the calculated threshold valueth is detected by the reference dot detection section 14A, the dot areameasuring section 14B calculates its area S (step S11), and the interiordivision ratio modification section 14C4 modifies the interior divisionratio k in accordance with the amount of modification of the interiordivision ratio calculated from the difference between the calculatedarea S and target value S_(t) (step S43). That is, a value obtained byadding, to the interior division ratio k, the amount of modificationobtained by multiplying the difference (S_(t)−S) between the calculatedarea S and the target value S_(t) by a predetermined coefficient α isemployed as a new interior division ratio k. The thus-obtained updatedinterior division ratio k is stored (step S44), and then the operationreturns to step S42 so that the threshold value th is updated.

As described above, the threshold value th which is updated for eachframe is supplied to the threshold value determining section 14D, and aresult of the binarizing process is supplied to the informationreproducing section 16 (step S16).

When the interior division ratio is modified as described above, thethreshold value is able to easily follow change in the quantity of lightas compared with the direct modification of the threshold value.Therefore, the amount of modification of the interior division ratio isreduced and convergence is performed quickly. Since the dot area doesnot depend on the change in the quantity of light, the binarizingprocess can stably be performed while reflecting the state of recordingof the dot code 170.

The tenth embodiment may be arranged as shown in FIG. 29.

That is, the peak value detection section 14C3 detects, from image data,maximum value max and minimum value min which are the peak values (stepS41). Then, the threshold value calculating section 14C5interior-divides the peak values by the interior division ratio k sothat the threshold value th is calculated (step S42). A reference dot 18binarized with the threshold value th is detected by the reference dotdetection section 14A, and the dot area measuring section 14B calculatesits area S (step S11).

Then, the interior division ratio modification section 14C4 determineswhether the difference between the calculated area S and the targetvalue S_(t) is smaller than a predetermined value ε_(s) (step S45). Ifthe difference is smaller than the predetermined value ε_(s), theforegoing threshold value th is supplied to the threshold valuedetermining section 14D so that a result of the binarizing processperformed by the threshold value determining section 14D is supplied tothe information reproducing section 16 (step S16).

If the difference is not smaller than the predetermined value ε_(s), theinterior division ratio is modified. In this case, whether or not thecalculated area S is smaller than the target value S_(t) (step S13) isdetermined. If the calculated area S is smaller than the target valueS_(t), the interior division ratio is increased by Δk (step S46). If thecalculated area S is not smaller than the target value S_(t), theinterior division ratio is decreased by Δk (step S47).

As described above, the peak values are detected from the image signal,the threshold value is calculated with the initial interior divisionratio, binarization is performed with the threshold value, the referencedot 18 is detected to measure its area, whether or not the differencebetween the calculated area and the target value is smaller than apredetermined value is determined, if it is smaller than thepredetermined value, then binarized data at this time is transmitted, ifit is not smaller than the predetermined value, then the interiordivision ratio is modified to again calculate the threshold value so asto binarize it. The foregoing repetition enables binarization of thetarget dot size to be reliably performed.

An eleventh embodiment of the information reproducing system accordingto the present invention will now be described.

In the eleventh embodiment, if the minimum value of the luminance issmaller than the threshold minimum value TH_(min), a determination is,as shown in FIG. 30, performed that the dot code 170 does not exist andonly the image of the surface of the information recording medium 12 ispicked up so that the process is interrupted. If the maximum value ofthe luminance is smaller than the threshold maximum value TH_(max), adetermination is performed that the dot code 170 is not sufficientlyirradiated with light and process is interrupted also in this case.

When the dot code 170 is scanned by a handy scanner, the image of thedot code 170 cannot be picked up in a plurality of leading and trailingframes among the plurality of the frames 40 which can continuously beobtained, thus causing a possibility to arise in that full white imagebeing formed, as shown in FIG. 31. If the scanner is moved upwardsduring the scanning operation, there is a possibility that a full blackimage is picked up.

Accordingly, the eleventh embodiment is structured such that when themaximum value and a minimum value of the luminance have been detectedfrom a predetermined region and when the detected values are larger thanpredetermined ranges, a determination is performed that the image of thedot code 170 is not correctly picked up and the following process isinterrupted. As a result, processes of an inappropriate screen forreading the dot code 170 can be interrupted. Thus, a wasteful processcan be omitted and the process speed can be raised.

FIG. 32 is a diagram showing the structure of the eleventh embodiment. Apeak value detection circuit 14C3a detects, from image data, maximumvalue max and minimum value min which are peak values. A comparator14C3b subjects the detected minimum value min and the threshold minimumvalue TH_(min) to a comparison. A comparator 14C3c subjects the detectedmaximum value max and the threshold maximum value TH_(max) to acomparison. An OR gate 14C3d transmit, to the following unit, a readingcontrol signal to instruct interruption of the following processes ofthe subject frame if a result of the comparison performed by thecomparator 14C3b is such that the minimum value min is larger than thethreshold minimum value TH_(min) or a result of the comparison performedby the comparator 14C3c is such that the maximum value max is smallerthan the threshold maximum value TH_(max).

FIG. 33 shows a flow chart for realizing the foregoing structure by asoftware manner. Initially, whether or not the process of the overallframe has been completed is determined (step S51). If the process hasnot been completed, the maximum value max and the minimum value min,which are the peak values, are detected from image data (step S41).Then, whether or not the minimum value min is larger than the thresholdminimum value TH_(min) is determined (step S52). If the minimum valuemin is larger than the threshold minimum value TH_(min), the operationreturns to step S51 so that a determination whether or not a next frameexists is performed.

If the minimum value min is not larger than the threshold minimum valueTH_(min), whether or not the detected maximum value max is smaller thanthe threshold maximum value TH_(max) is determined (step S53). If themaximum value max is smaller than the threshold maximum value TH_(max),the process of the subject frame is interrupted and operation returns tostep S51 so that a determination whether or not a next frame exists isperformed.

If the maximum value max is not smaller than the threshold maximum valueTH_(max), the foregoing binarizing process and the reading process areperformed (step S54).

A twelfth embodiment of the information reproducing system according tothe present invention will now be described.

In this embodiment, as shown in FIG. 34, the peak value detectionsection 14C3 has a selective average value calculating section 14C3edisposed in front of the peak value detection circuit 14C3a, theselective average value calculating section 14C3e being structured tocalculate the absolute value of the difference between adjacent pixelsof the pixel of interest. Only when a result of the calculation issmaller than a predetermined threshold value, the selective averagevalue calculating section 14C3e calculates the average value of theadjacent pixels. The peak values are detected from the calculatedaverage value of luminance.

If the image pickup section 204, for example, a CCD includes a defectivepixel when the image of the dot code 170 is picked up, the output of thepixel is changed considerably and adversely affects the peak valuedetection. Accordingly, the twelfth embodiment has a structure such thatthe amount of change of the pixel values adjacent to the pixel ofinterest is obtained. If the amount is smaller than a predeterminedthreshold value, the average value of the pixel values is supplied tothe peak value detection circuit 14C3a.

FIG. 35 is a flow chart of the operation of the twelfth embodiment.Initially, whether or not the peak value detection circuit 14C3a hascompleted detection of the peak values in one frame is determined (stepS61). If the detection has not been completed, the absolute value of thedifference between the front and rearward pixels of the i-th pixel y_(i)of interest, that is, y_(i−1) and y_(i+1) is obtained. Then, whether ornot the absolute value is smaller than fourth threshold value TH₄ isdetermined (step S62). If the absolute value is not smaller than thefourth threshold value TH₄, a determination is performed that the pixelvalue of the pixel y_(i) is not a maximal value and therefore the peakvalue detection circuit 14C3a does not detect the maximum and minimumvalues. Then, the value of the i register is increased (step S63), andthen the operation proceeds to a process of a next pixel.

If the absolute value of the difference between the pixel values y_(i−1)and y_(i+1) is smaller than the fourth threshold value Th₄, adetermination is performed that the foregoing portion is a portion inwhich the maximal value is obtained. Thus, average value avg iscalculated (step S64). The average value avg can be calculated asfollows: $\begin{matrix}{{avg} = \frac{y_{i - 1} + y_{i + 1}}{2}} & (2)\end{matrix}$

Whether or not the calculated average value avg is smaller than theminimum value min obtained in the previous process of the foregoingpixel is determined by the peak value detection circuit 14C3a (stepS65). If the average value avg is smaller than the minimum value min,the average value avg is employed as a new minimum value min (step S66).Then, the operation proceeds to step S63. If the average value avg isnot smaller than the minimum value min, whether or not average value avgis larger than maximum value max obtained in the process of the previouspixel is determined (step S67). If it is larger than the maximum valuemax, the average value avg is employed as a new maximum value max (stepS68). If it is not larger than the maximum value max, the operationproceeds to step S63 while employing the original maximum and minimumvalues.

As described above, if the image pickup section 204 has a defectivepixel during the reading operation, erroneous detection of the peakvalues can be prevented. That is, considerable change in the outputattributable to the defective pixel can be prevented and the influenceof a small change attributable to noise can be eliminated. Thus, thepeak values can stably be detected.

A thirteenth embodiment of the information reproducing system accordingto the present invention will now be described.

The thirteenth embodiment, as shown in FIG. 36A, has a structure suchthat the interior division ratio modification section 14C4 comprises ainterior division ratio modification amount table 14C4a. Thus, themeasured dot area S and a predetermined target value S_(t) are used todetermine the interior division ratio modification amount Δk inaccordance with the interior division ratio modification amount table14C4a.

The interior division ratio modification amount table 14C4a isstructured, for example, as shown in FIG. 36B. Thus, if the dot area Sis 7.0 and the target value S_(t) is 8.0, an amount of modification of0.13 is obtained and transmitted.

By obtaining the interior division ratio modification amount Δk from thetable as described above, calculations can be omitted and approximationto an optimum interior division ratio can be realized by only oneoperation.

A fourteenth embodiment of the information reproducing system accordingto the present invention will now be described.

The fourteenth embodiment has a structure such that the interiordivision ratio modification section 14C4 uses a predeterminedcoefficient α, the dot area S and the target value S_(t) to calculatethe interior division ratio modification amount Δk in accordance withthe following equation:Δk=α(S_(i)−S)   (3)

If the dot area S and the interior division ratio k has a linearrelationship as shown in FIG. 37, the modification amount Δk can beobtained from the relationship between the dot area S and the targetvalue S_(t) by using the foregoing linear equation.

By calculating the interior division ratio modification amount Δk byusing the linear equation, the memory for storing the table according tothe thirteenth embodiment can be omitted, the calculation can befacilitated and thus the size of the hardware can be reduced.

A fifteenth embodiment of the information reproducing system accordingto the present invention will now be described.

In the fifteenth embodiment, the foregoing coefficient α is not a fixedvalue. The coefficient α is made to be the same value as that in theprevious modification or a smaller value during repetition of themodification of the interior division ratio.

In a case where the dot area S and the interior division ratio k have arelationship as indicated by a thick line A shown in FIG. 38 and in acase where the dot area S obtained from binarization of the first framewith a certain interior division ratio k_(a) is located at a positionindicated by a dashed line B, the modification amount Δk₁ is calculatedfrom the foregoing value in accordance with inclination 1/α₁, forexample, “1/16”. As a result, the interior division ratio k at thesecond frame is made to be k_(b) and the measured dot area S is locatedat a position indicated by dashed line C. Then, the modification amountΔk₂ is calculated in accordance with inclination 1/α₂, for example,“1/32”. As described above, graduate approach to the target value S_(t)is performed.

As described above, a relatively larger coefficient α is employed in theinitial stage of the modification so that the convergence is completedquickly and the following up characteristic can be improved. If a largevalue is employed in the latter half of the modification, convergence isinhibited and oscillation takes place. Therefore, α is gradually reducedas the process proceeds to the latter half of the modification so thatoscillation is prevented.

FIG. 39 is a flow chart of the fifteenth embodiment.

The interior division ratio modification section 14C4 determines whetheror not the value of the reference dot number register S_(num) measuredby the dot area measuring section 14B is larger than the third thresholdvalue TH₃ (step S31). If the value is not larger than the thirdthreshold value TH₃, the interior division ratio k is not modified (stepS71) and transmitted to the threshold value calculating section 14C5.

If the value is larger than the third threshold value TH₃, countregister count is increased (step S72), and then a determination isperformed whether or not the value of the count register count is largerthan fifth threshold value TH₅ (step S73). If the value is not largerthan the fifth threshold value TH₅, the operation proceeds to step S71.If the value is larger than the fifth threshold value TH₅, the value ofa reference dot total area register SS measured by the dot areameasuring section 14B is divided by the value of a reference dot numberregister S_(num) similarly measured by the dot area measuring section14B so as to average area S_(avg) is calculated (step S26).

Simultaneously, the interior division ratio modification section 14C4determines whether or not the value of the foregoing counter registercount is larger than sixth threshold value TH₆ (step S74). If the valueis not more than the sixth threshold value TH₆, that is, by making thethreshold value TH₆ is made to be “1”, the coefficient α is set suchthat α₁=1/16 at the first modification (step S75). If the value islarger than the sixth threshold value TH₆, that is, in the second andensuing modifications, the coefficient α is set such that α₂=1/32 (stepS76).

After the average area S_(avg) and the coefficient α have beendetermined, a value obtained by multiplying the difference between thetarget value S_(t) and the average area S_(avg) (that is, S_(t)−S_(avg))by the foregoing coefficient α is added to the present interior divisionratio k so that a new interior division ratio k is obtained (step S77)and transmitted to the threshold value calculating section 14C5.

As described above, a relatively large coefficient is employed in theinitial stage of the modification so that the following upcharacteristic is improved. In the latter half of the modification inwhich the interior division ratios have been converged, a relativelysmall coefficient is employed so that oscillation is prevented.

A sixteenth embodiment of the information reproducing system accordingto the present invention will now be described.

In the sixteenth embodiment, the interior division ratio k is, as shownin FIG. 40, changed in a stepped manner and a hysteresis characteristicis provided.

By changing the interior division ratio k in the stepped manner, rapidchange of the interior division ratio k, which is changed attributableto, for example, noise can be prevented. Although the portion of thedescending portion of the step is sometimes considerably changedattributable to somewhat noise, the hysteresis characteristic isprovided for the foregoing portion so that the interior division ratio kfor this portion is stably determined.

By changing the interior division ratio in the step manner, calculationscan be facilitated and the size of the hardware can be reduced. Sincethe hysteresis characteristic is provided, change caused by noise can beprevented and therefore the binarizing process can stably be performed.

A seventeenth embodiment of the information reproducing system accordingto the present invention will now be described.

The seventeenth embodiment is structured such that the modification ofthe interior division ratio k is performed such that whether or not themodified interior division ratio is included in a predetermined range isdetermined, and if the interior division ratio is not included in therange, it is clipped.

That is, the interior division ratio k, as shown in FIG. 41, hascontinuous values from “0” to “1”. In a portion in which the interiordivision ratio k approximates “0”, the threshold value has a value nearthe minimum value min. In a portion in which the interior division ratiok approximates “1”, the threshold value has a value near the maximumvalue max. Since the foregoing binarizing operation is howeverconsidered not to be a normal binarizing operation, the value of themodified interior division ratio k is made to be a predetermined valueas described above, for example, “10/32” to “25/32”. If the value is notless than “25/32”, all of the values are fixed to “25/32.” If the valueis less than “10/32”, all of the values are fixed to “10/32”.

FIGS. 42 and 43 are a block diagram and an operation flow chart of theseventeenth embodiment.

In this embodiment, the interior division ratio modification section14C4 comprises an interior division ratio modification circuit 14C4b andan interior division ratio limiting section 14C4c. When the interiordivision ratio modification circuit 14C4b has added the modificationamount Δk so that the interior division ratio k has been modified (stepS46), a determination is performed whether or not the modified interiordivision ratio k is larger than seventh TH₇, for example, “25/32” (stepS81). If the modified interior division ratio k is larger than “25/32”,the interior division ratio k is set to the seventh threshold value TH₇(step S82) and it is transmitted to the threshold value calculatingsection 14C5.

If the value is not larger than the seventh threshold value TH₇, adetermination is performed whether or not the modified interior divisionratio k is smaller than eighth threshold value TH₈, for example, “10/32”(step S83). If the modified interior division ratio k is smaller thanthe eighth threshold value TH₈, the interior division ratio k is set tothe eighth threshold value TH₈ (step S84) and it is transmitted to thethreshold value calculating section 14C5.

If the value is not smaller than the eighth threshold value TH₈, theinterior division ratio k modified by the interior division ratiomodification circuit 14C4b is as it is transmitted to the thresholdvalue calculating section 14C5.

By clipping the interior division ratio k by a predetermined value,output of abnormal interior division ratio k owning to a stain, a patchyportion and blurring can be prevented and thus stable interior divisionratio k can be transmitted.

An eighteenth embodiment of the information reproducing system accordingto the present invention will now be described.

The reference dot 18 cannot correctly be detected in an inappropriateprinting condition or the image pickup condition. If the interiordivision ratio is modified to correspond to the area of the referencedot 18 which has been detected in the foregoing state, an inappropriateinterior division ratio can be set. The reference dot 18 cannotsometimes be detected from the image binarized with the foregoinginterior division ratio and thus restoration to a normal interiordivision ratio is sometimes inhibited.

Accordingly, the eighteenth embodiment has a structure such that theinterior division ratio is not modified in the foregoing state tocalculate a stable interior division ratio.

FIGS. 44 and 45 are a block diagram and an operation flow chart of theeighteenth embodiment.

The interior division ratio modification section 14C4 comprises aninterior division ratio modification circuit 14C4b and an interiordivision ratio holding section 14C4d. The interior division ratioholding section 14C4d has an interior division ratio modificationselection circuit 14C4d1 and an interior division ratio storage circuit14C4d2. In the interior division ratio modification selection circuit14C4d1, a determination is performed whether or not the number of thereference dots 18 detected by the reference dot detection section 14Aand counted by the dot area measuring section 14B satisfies apredetermined number (the third threshold value TH₃) (step S31). If thenumber is less than the predetermined number, the interior divisionratio k stored in the interior division ratio storage circuit 14C4d2 istransmitted to the threshold value calculating section 14C5 (step S71).If the number is larger than the predetermined number, the interiordivision ratio modification circuit 14C4b modifies the interior divisionratio k, that is, the interior division ratio modification circuit 14C4bgenerates a new interior division ratio obtained by adding the interiordivision ratio modification amount Δk (step S46) and transmits the sameto the threshold value calculating section 14C5.

When a satisfactorily large number of reference dots 18 cannot bedetected as described above, the modification of the interior divisionratio is inhibited so that the reliability of the interior divisionratio is maintained.

A nineteenth embodiment of the information reproducing system accordingto the present invention will now be described.

In the nineteenth embodiment, the interior division ratio modificationsection 14C4 modifies the interior division ratio until a field or aframe which satisfy a predetermined condition for continuous imagesignals read by the code reading section 10 is obtained. In thefollowing field or frame, the modified interior division ratio ismaintained.

As shown in FIG. 46, whether or not the number counted by the dot areameasuring section 14B satisfies a predetermined number (the thirdthreshold value TH₃) is determined (step S31). If the number is smallerthan the predetermined number, the interior division ratio k is notmodified and it is transmitted to the threshold value calculatingsection 14C5 (step S71).

If the number is not less than the predetermined value, the counterregister count is increased (step S72), and then whether or not thevalue of the counter register count is smaller than a predeterminedthreshold value TH_(cnt) is determined (step S91). If the value issmaller than the predetermined threshold value TH_(cnt), the interiordivision ratio modification amount Δk is added to the present interiordivision ratio k so that a new interior division ratio k is set (stepS46) and transmitted to the threshold value calculating section 14C5.

The foregoing process is repeated until the value of the counterregister count is not less than the predetermined threshold valueTH_(cnt). Then, the operation proceeds to step S71 so that the interiordivision ratio k is not modified and transmitted to the threshold valuecalculating section 14C5. That is, the number of the frames in which asufficiently large number of dots have been detected in counted. If thenumber is smaller than the predetermined threshold value THcnt, theinterior division ratio k is modified. If the count is not less than thepredetermined threshold value TH_(cnt) after the foregoing process hasbeen repeated, a determination is performed that the interior divisionratio k has been satisfactorily modified and converged. Thus, theinterior division ratio k is not modified in the following frames 40.

Since the recording condition is not considerably changed during thereading operation in a case where the dot code images are continuouslyread, the modification of the interior division ratio with which therecording condition is corrected is completed in the first half of theframes 40. Thus, the following modification is inhibited so that awasteful process is reduced and erroneous modification caused from noiseis prevented.

A twentieth embodiment of the information reproducing system accordingto the present invention will now be described.

In the twentieth embodiment, attitude dots 42 including informationabout the subject information recording medium 12 for determining thethreshold value for the binarizing section 14 are recorded in apredetermined region of the dot code 170 at a position near the readingstart end, as shown in FIG. 47. The binarizing section 14, as shown inFIG. 48, comprises an attitude dot detection section 14G for detectingthe attitude dots 42, an attitude reading section 14H for subjecting theimage signals ready by the code reading section 10 to the binarizingprocess for field or frame units so as to read, from the obtainedbinarized image, information about the information recording medium 12from the attitude dots 42 detected by the attitude dot detection section14G, and an attitude storage section 14I for storing information read bythe attitude reading section 14H so as to similarly apply it to each ofthe following images.

That is, information about the information recording medium 12,including the material of the information recording medium 12, thedensity of the ink at the recording operation, the amount of exposureand the like are, as the attitude dots 42, recorded in the predeterminedregion of the dot code 170 adjacent to the reading start end. Thus, theattitude dots 42 are first scanned and read when the dot code 170 isscanned. Information of the information recording medium 12 denoted bythe read attitude dots 42, that is, information including the materialof the information recording medium 12 and the density of the ink isstored in the attitude storage section 14I so as to be used when theinterior division ratio is determined.

As described above, the attitudes (or attribute) of the material of theinformation recording medium 12, the characteristics of the recordingmaterial and the recording method can be detected prior to binarizingthe dot code 170 so that appropriate parameters for the binarizingprocess are provided.

A twenty-first embodiment of the information reproducing systemaccording to the present invention will now be described.

The twenty-first embodiment is structured to solve a problem in thatirregularity of the illumination system and inclination of the imagepickup unit with respect to the information recording medium 12 causethe picked up image to be shaded and the binarizing operation isadversely affected. As shown in FIG. 49, the shaded code image isdivided into a plurality of regions 44 including four regions in thelateral direction and three regions in the longitudinal direction. Thatis, since an assumption can be made that the recording condition and theillumination condition are the same among the divided region units, acharacteristic amount is extracted for each of the divided regions so asto calculate the threshold value.

FIG. 50 is a block diagram showing the binarizing section 14 accordingto the twenty-first embodiment. The region dividing section 14J dividesthe pick up screen of the dot code 170 into a plurality of regions. Acharacteristic amount extracting section 14K extracts a binarizationcharacteristic amount of each of the regions divided by the regiondividing section 14J. For each divided region, threshold valuecalculating section 14L calculates the threshold value for thebinarizing process in accordance with the characteristic amountextracted by the characteristic amount extracting section 14K. Then, thethreshold value calculating section 14L supplies the calculatedthreshold values to the threshold value determining section 14D so thatthe image signal is binarized.

Since an assumption can be performed that the recording condition andthe illuminating condition are constant for the divided region units asdescribed above, the characteristic amount is extracted for the dividedregion units to calculate the threshold value so that the influence ofshading and the like is eliminated satisfactorily.

A twenty-second embodiment of the information reproducing systemaccording to the present invention will now be described.

In the twenty-second embodiment, reference regions 46 for extracting thecharacteristic amount (for example, a maximum value and a minimum value)for use in the binarizing process is provided for a portion of the datacode 20, as shown in FIG. 51. When the region dividing section 14Jdivides the frame 40 into the regions, the frame 40 is divided in such amanner that at least one reference region 46 is included in one dividedregion 44.

The division of the frame 40 is performed such that if the interval ofthe reference regions 46 are X pixels in the lateral direction and Ypixels in the longitudinal direction on the picked up screen or frame 40when an image including the reference regions 46 is picked up with askew angle of 0 degree, then the size of the each divided region 44 mustbe at least X pixels in the lateral direction and Y pixels in thelongitudinal direction.

As a result, at least one reference region 46 is included in eachdivided region 44 so that the stable characteristic amount is extracted.

By detecting the maximum value of the luminance as the characteristicamount, the binarizing process can be performed on which the lightquantity of the divided region 44 is reflected. Thus, a satisfactoryresult can be obtained even if shading takes place.

A twenty-third embodiment of the information reproducing systemaccording to the present invention will now be described.

In the twenty-third embodiment, as shown in FIG. 52, at least either ofthe marker 174 and an inhibition region adjacent to the marker 174 isused as the reference region 46.

The above-mentioned marker 174 is a relatively wide region in whichconnected black portions exist, while the inhibition region adjacent tothe marker 174 is a relatively wide region in which connected whileportions exist. Accordingly, the characteristic amount is extracted fromthe marker 174 above or the adjacent inhibition region so that a stablebinarizing process is performed. If a low-pass filter is provided todetect the maximum and minimum luminance, the minimum value can bedetected from the marker 174 and the maximum value can be detected fromthe inhibition region adjacent to the marker 174.

By making the reference region 46 to be the marker 174 or the adjacentregion, the necessity of recording the reference region 46 individuallyfrom the code can be eliminated. Thus, the recording area caneffectively be used and the direction can easily be performed.

A twenty-fourth embodiment of the information reproducing systemaccording to the present invention will now be described.

The twenty-fourth embodiment, as shown in FIG. 53A, has a structure suchthat the shaded code image is divided as is performed in thetwenty-first embodiment and the characteristic amount is extracted individed region units in such a manner that the maximum value of theluminance is extracted for the divided region units.

The state of shading is correspondingly denoted by the maximum values ofthe luminance in the region rather than the minimum values, the maximumvalues being widely distributed in the dot code 170. Accordingly, asshown in FIG. 53B, the maximum value max of the luminance is obtainedfrom each of the divided regions and the threshold value is determinedto correspond to the maximum value max. If a value which is 50% of themaximum value of the luminance is employed as the threshold value thwhich is then binarized, coping with more intense shading can beperformed.

As described above, the characteristic amount is made to be the maximumvalue of the luminance so that the reference region 46 is made to be theground color portion of the information recording medium 12. Since theground color portion is widely distributed over the dot code, stablecharacteristic amounts can be extracted even if the divided region 44 ismade to be a relatively small region. Since the state of the quantity ofillumination in each of the divided regions 44 is satisfactorilyreflected on the maximum values, the threshold value adaptable toshading can effectively be calculated.

A twenty-fifth embodiment of the information reproducing systemaccording to the present invention will now be described.

The twenty-fifth embodiment is structured such that a characteristicamount extracting section 14K extracts the maximum value of theluminance of each of the divided regions as a first characteristicamount and extracts the minimum value of the luminance from the overallscreen as the second characteristic amount. A threshold valuecalculating section 14L calculates the threshold value for each of thedivided regions from the maximum and minimum values of the luminance inaccordance with a predetermined interior division ratio.

That is, the maximum value of the luminance is detected from each of thedivided regions 44, while the minimum value is obtained from the pickedup screen, that is, the overall surface of the frame. The thus-obtainedmaximum and minimum values are used to calculate the threshold value inaccordance with the predetermined interior division ratio k.

If the maximum value max and the minimum value min are obtained in eachof the divided regions 44 of the image shaded as shown in FIG. 54A, aresult as shown in FIG. 54B is obtained. In this case, since thecharacteristic amount can significantly be extracted from the region,such as the marker 174 in which black portions successively exist, theminimum value is obtained from the divided regions in each of which themarker 174 exists so as to be used as the minimum value fr_min of theoverall portion of the frame which corresponds to the minimum value ofeach of the divided regions 44.

The state of shading is significantly be reflected by the maximum valueof the luminance in the region and the maximum value is distributed overa wide range in the code. On the other hand, the minimum values of theluminance appear only in the marker regions 48 and thus distributedeccentrically. However, change is the luminance attributable to shadingcan be restrained. Accordingly, the maximum value is detected from eachof the divided regions 44, while the minimum value of the luminance isdetected from the overall portion of the frame. Thus, even if thedivided regions 44 are made to be small such that the marker region 48is not included, the threshold value corresponding to shading cantherefore be set.

As described above, the maximum and minimum values of the luminance areused to calculate the threshold value in accordance with the interiordivision ratio so that the threshold value is calculated to be adaptableto the quantity of light.

By extracting the maximum value of the luminance from each of thedivided regions, coping with shading can be performed. The minimum valueof the luminance which cannot stably be extracted from each of thedivided regions is extracted from the overall portion of the screen.Thus, even if the black level is raised in the recording condition,coping with it can be performed.

A twenty-sixth embodiment of the information reproducing systemaccording to the present invention will now be described.

In a case where the minimum value of the luminance is detected from theoverall portion of the frame, the threshold value in each of the dividedregions 44 cannot be calculated until the process of the overall portionof the frame is completed. Accordingly, the twenty-sixth embodiment isstructured such that the dot codes 170 are successively read in such amanner that the characteristic amount extracting section 14K, as shownin FIG. 55, detects the maximum value max of the luminance from each ofthe divided regions 44. On the other hand, the minimum value min of theluminance is made to be the minimum value fr_min of the overall portionof the previous frame. Then, the threshold value calculating section 14Lcalculates the threshold value in each of the divided region units fromthe maximum and minimum values of the luminance in accordance with apredetermined interior division ratio.

As described above, the minimum value extracted from the previous fieldor frame is used so that the present field or frame are subjected to thebinarizing process in the divided region units.

A twenty-seventh embodiment of the information reproducing systemaccording to the present invention will now be described.

In a case where the present frame is binarized with the threshold valuecalculated from the peak value of the previous frame, division of theregion for preventing the influence of shading results in the state ofshading being not changed as shown in FIG. 56A among frames. Thus, theillumination condition for the divided region s_fr2 is considered to beconstant.

As scanning is performed, point A on the information recording medium ismoved to the upper portion of the frame, as shown in FIG. 56B. If theinformation recording medium 12 has ground color irregularity 50 at thistime, also the ground color irregularity 50 is moved, thus causingdifferent irregularity to be generated in the same divided region of thenext frame. No problem arises in a case where the peak value is detectedfrom the overall portion of the frame. However, in a case where the peakvalue is detected in the divided region units, the difference in thedivided regions in which the ground color irregularity 50 exists betweenthe previous frame and the present frame causes the threshold value tobe determined in accordance with the peak value detected from each ofthe divided regions to be changed considerably.

Accordingly, in the twenty-seven embodiment, the characteristic amountextracting section 14K, as shown in FIG. 57, comprises a maximum valuedetection circuit 14K1 for detecting the maximum value of the luminancein each of the divided regions and a maximum value averaging section14K2 for averaging the extracted maximum values for at least two fieldsor frames adjacent in terms of time, for example, for three frames. Themaximum value averaging section 14K2 stores the maximum value for, forexample, two previous frames extracted by the maximum value detectioncircuit 14K1 in the maximum value storage circuit 14K2a for each of thedivided regions. The maximum value averaging circuit 14K2b calculates anaverage value of the stored maximum value and the maximum value of thepresent frame extracted by the maximum value detection circuit 14K1 foreach of the divided regions.

By averaging the maximum value of the luminance of the at least two ormore fields or frames adjacent in terms of time, for example, byaveraging the maximum value of the luminance of the same divided regionsover three frames, change in the maximum value attributable to theground color irregularity 50, that is, change in the threshold valueattributable to the change in the maximum value can be prevented.

A twenty-eighth embodiment of the information reproducing systemaccording to the present invention will now be described.

The binarizing method in which the threshold value is calculated fromthe maximum and minimum values detected from the detection region of thepresent frame with a predetermined interior division ratio and the sameregion of the next frame is binarized encounters a risk that thethreshold value is set to the background level when the code is notincluded in the detection region because the code level is made to bethe substantially the same as the background level.

In an example case, as shown in FIG. 58, where the ground color ofcertain divided regions in which the pick up image exists is graduallybrightened as the time and the image of the code has been picked up inthe first frame frame_i and the third frame_i+2 but the code has notbeen picked up in the second frame frame_i+1, the maximum value max ofthe luminance is gradually enlarged as “200, 210, 220”. The minimumvalue min is unintentionally made as “30, 190, 33”. Thus, an excessivelylarge value is realized at the second frame frame_i+1. Therefore, whenthe next frame frame_i+2 is binarized with the threshold valuecalculated from the maximum and minimum values of the second frameframe_i+1, the binarization cannot correctly by performed.

Therefore, the twenty-eighth embodiment has a structure such thatexistence of the dot code 170 is detected. If the dot code 170 notexists, the minimum value min is replaced by the minimum value of theprevious frame. As a result, the minimum value min of the second frameframe_i+1 is replaced from “190” to “30”. Therefore, “120” is obtainedas the threshold value of the third frame frame_i+2 which is able tofollow the actual threshold value “126”. Since the maximum value is notreplaced, the threshold value is able to follow the state where thequantity of light is gradually changed.

FIG. 59 is a diagram showing the structure of the binarizing section 14according to the twenty-eighth embodiment for replacing the minimumvalue when the dot code 170 does not exist. That is, a peak valuedetection section 14M detects the maximum and minimum values of theluminance from a predetermined detection region. A code detectionsection 14N detects whether the dot code 170 exists in the detectionregion. A minimum value replacement section 140 replaces the minimumvalue in the detection region with the minimum value of the previousfield or frame in the case where the code detection section 14N has notdetected the dot code 170. A threshold value calculating section 14Lcalculates the threshold value for the binarization in the same regionof the next field or frame from the maximum value and the replacedminimum value in accordance with a predetermined interior divisionratio.

By replacing the minimum value when the dot code 170 does not exist,setting of the threshold value to the background level when the dot code170 has been out of the detection region and thus the minimum value (thecode level) is made to be the substantially the same as the maximumvalue (the background level) can be prevented. Moreover, reference tothe background level enables the threshold value to follow change in thequantity of light.

A twenty-ninth embodiment of the information reproducing systemaccording to the present invention will now be described.

The twenty-ninth embodiment is structured such that, if the codedetection section 14N does not detect the dot code 170, the minimumvalue replacement section 140 does not replace the minimum value in thedetection region with the minimum value of the subject region of theprevious frame as is performed in the twenty-eighth embodiment. In thetwenty-ninth embodiment, as shown in FIG. 60, replacement with theminimum value of the detection region adjacent to the subject region isperformed.

By replacing with the minimum value of the spatially adjacent region isperformed if the dot code 170 does not exist, setting of the thresholdvalue to the background level when the dot code 170 is out of thedetection region and thus the minimum value (the code level) is made tobe the substantially the same as the maximum value (the backgroundlevel) can be prevented. Moreover, reference to the background levelenables the threshold value to follow change in the quantity of light.

A thirtieth embodiment of the present invention will now be described.

The thirtieth embodiment has a structure such that the code detectionsection 14N according to the twenty-eighth or the twenty-ninthembodiment determines whether or not the ratio of the maximum value (thebackground level) and the minimum value (code level) detected by thepeak value detection section 14M is larger than a predeterminedthreshold value. If the ratio is not larger than the threshold value, aconsideration is made that the dot code 170 does not exist in thedetection region.

As shown in FIG. 61, in steps S61 to S68, peak values max and min aredetected by the peak value detection section 14M. The code detectionsection 14N determines whether or not the ratio of the maximum value tothe minimum value, that is, max/min is larger than a predetermined ninththreshold value TH₉ (step S101). If the ratio is larger than the ninththreshold value TH₉, the threshold value calculating section 14L usesthe detected peak values max, min and the interior division ratio k tocalculate the threshold value th for the binarizing process inaccordance with the foregoing equation (1) (step S42).

If the ratio of the maximum value to the minimum value is smaller thanthe ninth threshold value TH₉, the minimum value replacement section 14Oreplaces the detected minimum value min with the minimum value min ofthe previous frame or minimum value fr_min of the detection regionadjacent to the subject frame (step S102). Then, the operation proceedsto step S42 so that the threshold value th for the binarizing process iscalculated.

Thus, the known peak value can be used to easily and reliably determinethe existence of the code.

Preferred aspects formed by combining the first to thirtieth embodimentsare as follows, and the combination will be described as a thirty-firstembodiment.

FIG. 62 is a flow chart showing a process for calculating the interiordivision ratio according to the thirty-first embodiment. To detect thereference dots 18, for example, the pattern dots 278, the reference dottotal area register SS and the reference dot number register S_(num) areinitialized to “0” (step S21). Then, whether or not the detection hasbeen completed is determined (step S22). If the detection has not beencompleted, area S_(i) of the i-th reference dot 18 is calculated (stepS23). Then, whether or not the calculated area S_(i) is in apredetermined range, that is whether or not the same is between thefirst threshold value TH₁ and the second threshold value TH₂ isdetermined (step S24). If the calculated area S_(i) is not in theforegoing range, the calculated area S_(i) is deleted as an erroneouslycalculated dot area attributable to a stain, a patchy portion andblurring. Then, the operation returns to step S22 so that a process fora next reference dot 18 is performed. If the area S_(i) is in theforegoing range, the calculated area S is added to the value of theregister SS. Moreover, the value of the reference dot number registerS_(num) is increased (step S25), and then the operation returns to stepS22.

When the detection of the reference dots 18 has been completed, whetheror not the value of the reference dot number register S_(num) indicatingthe total sum of the reference dots 18 is larger than a predeterminednumber, that is, the third threshold value TH₃ is determined (step S31).If the value is smaller than the third threshold value TH₃, a fact isconfirmed that the sufficiently large number of dots have not beendetected. Therefore, if the average area is obtained by using theforegoing value, reliability deteriorates. Therefore, if the value isnot larger than the third threshold value TH₃, “0” is added to theinterior division ratio k, that is, the interior division ratio k is notmodified (step S71).

If the value is larger than the third threshold value TH₃, the counterregister count is increased (step S72), and whether or not the value ofthe counter register count is larger than the fifth threshold value TH₅is determined (step S73). The fifth threshold value TH₅ is “1”. The factthat the value is smaller than the fifth threshold value TH₅ meanspassing through the loop at the first time. In this case, since asufficiently large number of dots have been detected from the frame 40,the operation proceeds to step S71 so that the interior division ratio kis not changed.

If the value is larger than the fifth threshold value TH₅, the value ofthe reference dot total area register SS is divided by the value of thereference dot number register S_(num) so that average area S_(avg) iscalculated (step S26).

Simultaneously, whether or not the value of the counter register countis larger than sixth threshold value TH₆ is determined (step S74). Ifthe value is smaller than the sixth threshold value TH₆, that is,assuming that the sixth threshold value TH₆ is “2”, the coefficient α isset such that α₁=1/16 at the first time (count=2) (step S75). If thevalue is larger than the sixth threshold value TH₆, that is, at thesecond and ensuing time (count>1), α is set such that α₂=1/32 (stepS76).

In the thirty-first embodiment, the dot area, which is changed due tothe change in the magnification and distortion when the image has beenpicked up, is corrected to normalize the area by the distance betweenthe markers. To detect the marker pairs, the intermarker total distanceregister SL and the intermarker distance detection number registerL_(num) are initialized to “0” (step S111). Then, whether or not thedetection has been completed is determined (step S112). If the detectionhas not been completed, the distance L between the markers is calculated(step S113). Then, the calculated distance L is added to the totaldistance register SL between markers, and the value of the intermarkerdistance detection number register L_(num) is increased (step S114), andthen the operation returns to step S112.

After the detection of the marker pairs has been completed, the value ofthe total distance register SL between markers is divided by the valueof the intermarker distance detection number register L_(num) so thataverage intermarker distance L_(avg) is calculated (step S115). Inaccordance with the calculated average intermarker distance L_(avg), atarget value S_(t) of the area of the reference dot 18 is calculated byusing a predetermined function S(L_(avg)) (step S116). The predeterminedfunction S(L_(avg)) is, for example, S(L_(avg))=a(L_(avg))² orS(L_(avg))=b·L_(avg)+c or the like obtained due to approximation of theforegoing function in a specific region (where a, block and code arecoefficient such that a=1/12, b=3, c=2 or the like).

When the average area S_(avg), the coefficient α and the target valueS_(t) have been calculated, a value obtained by multiplying thedifference (that is, S_(t)−S_(avg)) between the target value S_(t) andthe average area S_(avg) by the foregoing coefficient α is, as themodification amount of the interior division ratio, added to the presentinterior division ratio k so that a new interior division ratio k isobtained (step S77).

When the interior division ratio k has been obtained in step S71 or stepS77, it is clipped to be included in a predetermined range so that afinal interior division ratio k is determined. That is, whether or notthe calculated interior division ratio k is larger than the sevenththreshold value TH₇, for example, “25/32” is determined (step S81). Ifthe interior division ratio k is larger than the seventh threshold valueTH₇, the value of the seventh threshold value TH₇ is determined to thefinal interior division ratio k (step S82). If it is not larger than theseventh threshold value TH₇, whether or not the calculated interiordivision ratio k is smaller than an eighth threshold value TH₈, forexample, “10/32”, is determined (step S83). If it is smaller than theeighth threshold value TH₈, the value of the eighth threshold value TH₈is determined to be the final interior division ratio k (step S84). Ifit is not smaller than the eighth threshold value TH₈, the calculatedinterior division ratio k is as it is determined to be the finalinterior division ratio k.

FIG. 63 is a flow chart for a process for calculating the thresholdvalue in the thirty-first embodiment.

Initially, whether or not the detection of the peak value has beencompleted is determined (step S61). If the detection has not beencompleted, the absolute value of the difference between the pixels infront of the i-th pixel y_(i) of interest and in the rear of the same,that is, y_(i−1) is obtained to determine whether or not the absolutevalue is smaller than the fourth threshold value TH₄ (step S62). If theabsolute value is not smaller than the fourth threshold value TH₄, aconsideration is performed that the pixel value of the pixel y_(i) isnot a minimal value and the detection of the maximum and minimum valuesis not performed but the value of the i register is increased (stepS63). Then, the operation proceeds to a process of a next pixel.

If the absolute value of the difference between the pixel values y_(i−1)and y_(i+1) is smaller than the fourth threshold value TH₄, aconsideration is performed that the foregoing portion is a portion inwhich a maximal value is taken. Thus, the average value avg iscalculated (step S64).

Then, whether or not the calculated average value avg is smaller thanthe minimum value min obtained in the process of the previous pixel isdetermined (step S65). If it is smaller than the minimum value minimumvalue, the average value avg is made to be a new minimum value min (stepS66). Then, the operation proceeds to step S63. If it is not smallerthan the minimum value min, whether or not the average value avg islarger than the maximum value max obtained in the process of theprevious pixel is determined (step S67). If it is larger than themaximum value max, the average value avg is made to be a new maximumvalue max (step S68). Then, the operation proceeds to step S63. If it isnot larger than the maximum value max, the original maximum and minimumvalues are maintained and then the operation proceeds to step S63.

By repeating the foregoing process, the peak value of the luminance,that is, the maximum value max and minimum value min are detected.

After the detection of the peak value has been completed, whether or notthe ratio max/min of the maximum value to the minimum value is smallerthan the ninth threshold value TH₉ is determined (step S101). If theratio is larger than the ninth threshold value TH₉, the detected peakvalue max, minimum value and the interior division ratio k of theprevious frame calculated by the process for calculating the interiordivision ratio are used to calculate the threshold value th inaccordance with the foregoing equation (1) (step S42).

If the ratio of the maximum and minimum values is smaller than the ninththreshold value TH₉, the detected minimum value min is replaced by theminimum value fr_min of the previous frame (step S102). Then, theoperation proceeds to step S42 so that the threshold value th iscalculated.

Then, the threshold value th is multiplied by light quantity change rateβ so that the threshold value threshold for the binarizing process iscalculated (step S117). Symbol β indicates a change rate when thequantity of light is changed by the light source 198 and it is expressedas follows when the quantity of light for the frame from which the peakvalue has been detected is L1 and the quantity of light of the framewhich is binarized by using the calculated threshold value is L2:$\beta = \frac{L2}{L1}$

FIG. 64 is a flow chart of the binarizing process according to thethirtieth embodiment.

Initially, whether or not correction of a defect of a pixel has beencompleted is determined (step S118). If the correction has not beencompleted, average pixel value avg of pixels y_(i−1) and y_(i+1) infront and in the rear of the i-th pixel y_(i) of interest is calculated(step S119). Then, whether or not the difference between the calculatedaverage value avg and the value of the pixel y_(i) of interest is largerthan tenth threshold value TH₁₀ is determined (step S120). If it is notlarger than the tenth threshold value TH₁₀, a fact can be said that thepixel y_(i) of interest has no defect. Therefore, a process of the nextpixel is performed by increasing i (step S121), and then the operationreturns to step S118. If it is larger than the tenth threshold valueTH₁₀, a fact can be said that the pixel y_(i) of interest has a defect.Therefore, a replacement from pixel value of the pixel y_(i) of interestto the calculated average value avg is performed (step S122). Then, theoperation proceeds to step S121.

After correction of defects of all of the pixels has been completed,image data of the pixel is equalized by an equalizer (step S123). Then,the threshold value for the binarizing process obtained in the processof the previous frame is binarized.

That is, whether or not the binarizing process has been completed isdetermined (step S124). If the binarizing process has not beencompleted, whether or not the value of the pixel y_(i) of interest issmaller than the threshold value threshold for the binarizing process isdetermined (step S125). If the value is smaller than the threshold valuethreshold, data di for binarization is determined to be “1” (step S126).If the value is smaller than the threshold value threshold, it isdetermined to be “0” (step S127). Then, to process the next pixel, i isincreased (step S128), and then the operation returns to step s124.

After all of the pixels have been binarized, binarized data di for allof the pixels in the subject frame 40 is transmitted.

As described above, the thirty-first embodiment comprises the interiordivision ratio calculating processing section, the threshold valuecalculating processing section and the binarization processing section.If each of the processes is performed in three continuous frames (orfields in the case where the process is performed in each field), theimage memory can be omitted and thus the binarization can be performedreal time. The foregoing process is realized by using the characteristicthat the threshold value of the present frame can be determined by usingthe state of the previous frame because the illumination condition andthe recording condition are not considerably changed among thesuccessive frames in a case where the images of the dot codes 170 arecontinuously picked up.

That is, as shown in FIG. 65, a threshold value determining section 52binarizes an image signal of the present frame (frame i) with anappropriate threshold value for the binarization. Then, a reference dotis detected from the binarized image, and the interior division ratio ismodified from the area by an interior division ratio modificationsection 54. Then, the modified interior division ratio is stored by aninterior division ratio storage section 56. Then, a peak value detectionsection 58 detects the peak value from the image signal of a next frame(frame i+1). A threshold value calculating section 60 calculates thethreshold value from the peak value and the stored interior divisionratio (of the frame i). The calculated threshold value is stored in athreshold value storage section 62. Then, an image signal of a nextframe (frame i+2) is binarized by the stored threshold value (of framei+1).

As described above, the code reading section 10 successively reads thedot codes, and the binarizing section 14 modifies the interior divisionratio of the two frames before the read and continuous image signalswith the area of the detected reference dot. In accordance with themodified interior division ratio, the peak value of the previous frameis interior-divided so that the threshold value is calculated. Inaccordance with the calculated threshold value, the present frame isbinarized. Therefore, the memory for storing the images can be omittedand the real time process can be performed.

When the binarization is performed by using the modified interiordivision ratio and the interior division ratio is again modified, adelay of two frames takes place in the foregoing structure. Therefore,it is preferable that the interior division ratio be controlled whilebeing separated into two independent systems consisting of odd-numberframes and even-number frames.

That is, as can be understood from FIG. 66A, binarized data istransmitted from every other frames. Therefore, blocks which can be readin only the missed frames is skipped from reading. To prevent this, thescanning speed may be sufficiently reduced to prevent omitting fromreading of the block if the code is read from every other frames. As analternative to this, binarization operations shifting from each other byone frame may be in parallel performed as shown in FIG. 66B. Theparallel binarizing operations enables the process to be a commonprocess because the same process is not performed in the same frames.Therefore, values different in only the interior division ratios arerequired to be held. Therefore, the two systems of interior divisionratios are held and the interior division ratio of the different typemay be used for the odd-number frames and the even-number frames.

A flow of the process in the foregoing case will now be described withreference to a time chart shown in FIG. 67. That is, as can beunderstood from FIG. 67, the parallel binarizing processes are performedsuch that the same process is not performed between a system 1 and asystem 2 in the same frame. Therefore, the processes can sequentially beperformed in accordance with the time chart. Each value are held in aperiod as shown in FIG. 67 and thus only the different interior divisionratios must be held for the two systems.

As a result, the scanning speed can be maintained, omission of readingof the block can be prevented, the memory for storing the image can beomitted and the real time process can be performed.

The information recording medium 12 will now be described.

A first embodiment of the information recording medium according to thepresent invention is used in the information reproducing systemcomprising the code reading section 10 for reading the dot code 170 fromthe information recording medium 12 on which multimedia informationincluding at least any one of audio information, image information anddigital code data is recorded in the form of the dot code 170 which canoptically be read; the binarizing section 14 for generating binarizeddata from the image signal corresponding to the dot code 170 read by thecode reading section 10; and the information reproducing section 16 forrestoring binarized data generated by the binarizing section 14 tooriginal multimedia information so as to reproduce the originalmultimedia information. In particular, the information recording medium12 is characterized by the reference dot 18 which serves as a referencewhen the threshold value is modified in such a manner that the area ofthe detected dot approaches a predetermined target value.

By providing the reference dot 18 as described above, binarization onwhich the dot area is accurately reflected can be performed withoutdependency upon the dot expansion and contraction in the recordingcondition.

As shown in FIG. 10A, modulation is performed in such a manner than anisolated dot is formed in the data dots 282 and the isolated dot is usedas the reference dot 18. In this case, the isolated dot in the dot codeis used and therefore the recording area can effectively be used.

Moreover, another region for the reference dot is provided individuallyfrom the data dots 282, as shown in FIG. 10B and the isolated dot isrecorded in the provided region so that the reference dot 18 is formed.In the foregoing case, existence of the reference dot 18 at apredetermined position individually from the data dots 282 enables thedetection to be performed easily.

As an alternative to this, the reference dot 18 may be provided in thevicinity of the reading end of the data dots 282 as shown in FIG. 11A toform a recording format arranged such that the reference dot 18 isinitially scanned. In the foregoing case, the threshold value can bemodified when scanning of the data code 20 is started. Moreover, therecording area can effectively be used afterwards as the data coderecording region.

As shown in FIG. 11B, blocks of the data dots 282 each having a somewhatsize may be formed so as to repeatedly form the reference dots 18. Inthe foregoing case, periodical existence of the reference dots 18enables modification of the threshold value to be performed whenrequired.

A second embodiment of the information recording medium according to thepresent invention will now be described.

In the second embodiment, in place of using the reference dot 18 as thereference for modifying the threshold value, the binarizing section 14detects the maximum and minimum values of the image signal levelcorresponding to the dot code 170. Code data binarized by the thresholdvalue calculated from the maximum and minimum and in accordance with apredetermined interior division ratio is used to detect a dot. Thus, itis used as a reference for modifying the interior division ratio in sucha manner that the area of the detected dot area approaches apredetermined target value.

Thus, binarization on which the dot area is accurately reflected can beperformed without dependency upon dot expansion and contraction of therecording condition and also without dependency of the illuminationcondition when the image is picked up.

A third embodiment of the information recording medium according to thepresent invention will now be described.

In the third embodiment, the information recording medium 12, as shownin FIGS. 68A and 68B, has recorded images of a plurality of referencedots 18 in the image pickup region (the frame 40).

Since recording is performed in such a manner that a plurality of thereference dots 18 exist in the image pickup region, that is, in theframe, the accuracy of the area can be improved by using the averagearea as described in the seventh embodiment of the informationreproducing system.

That is, the averaging operation compensates the change in the areaoccurring attributable to the relative position. Even if a stain, apatchy portion and blurring take place, the defective portion may beomitted because a sufficiently large number of the reference dots 18 canbe detected. Therefore, the average area can stably be calculated. Asdescribed above, the plural reference dots 18 can be detected in theimage pickup region and the binarizing section 14 calculates the averagearea so that influence of noise is compensated and further accuratecalculation of the area is enabled.

A fourth embodiment of the information recording medium according to thepresent invention will now be described.

In the fourth embodiment, the information recording medium 12 has areference region 46 from which the characteristic amount for thebinarization is extracted by the binarizing section 14.

That is, as has been described in the twenty-second embodiment of theinformation reproducing system, the reference region 46 for extractingthe characteristic amount for the binarization is provided for theinformation recording medium 12. As the reference region 46, either of ablack region or a white region each having a area larger than that ofthe data dots 282, for example, the marker 174 or an inhibition regionadjacent to the marker 174 may be employed, as shown in FIG. 69A. Asshown in FIG. 69B, the outer periphery of the data code 20 may beemployed.

Since the reference region 46 exists individually from the code, astable characteristic amount, for example, the maximum and minimumvalues of the luminance can be extracted.

A fifth embodiment of the information recording medium according to thepresent invention will now be described.

The fifth embodiment is structured such that the information recordingmedium 12 according to the first or the second embodiment has a dotinterval measuring dot for measuring the dot interval for correcting atleast either of the reference dot area detected by the binarizingsection 14 or the predetermined target value.

That is, as has been described in the sixth embodiment of theinformation reproducing system, the interval between dots is measured tocorrect the area of the reference dot 18 when the reference dot 18 hasbeen detected, this embodiment is characterized in that the intervalmeasuring dot 38 is recorded.

As the interval measuring dot, the marker 174 may be used, as shown inFIG. 70A, or a predetermined dot amount the reference dots 18, forexample, a dot positioned to the right of the marker may be used, asshown in FIG. 70B.

As described above, the distance between predetermined dots is measure,the image pickup magnification and state of distortion can be detected.In accordance with the detected state, the dot area or the target valueis corrected so that binarization is performed to correspond to changein the magnification and distortion.

The information recording apparatus will now be described.

The information recording apparatus according to the present inventionuses the above-mentioned information reproducing system. In a firstembodiment of the information recording apparatus is structured suchthat at least two types of reference dots D₁, D₂, . . . , D_(n), . . .at least having different area or shape, for example, different areas asshown in FIG. 71A are recorded on the information recording medium 12.By using the foregoing information reproducing system, the recordedreference dots 18 are read so as to be binarized. As shown in FIG. 71B,areas S₁, S₂, S_(n), . . . of each of the read reference dots 18 and apredetermined reference value S_(r) are subjected to comparisons. Then,reference dots 18 having the difference smaller than a predeterminedthreshold value are selected. In accordance with the selected referencedots 18, a dot code 170 corresponding to multimedia information whichmust actually be recorded is recorded on the information recordingmedium 12.

FIG. 72 is a block diagram showing the above-mentioned informationrecording apparatus. FIG. 73 is an operation flow chart.

Initially, a printing section 64 prints a plurality of reference dotsD₁, D₂, . . . , D_(n), . . . having different areas (step S131). Then,an image input section 66 picks up the images of the printed referencedots 18 (step S132). A maximum value and minimum value detection section68 obtains maximum value max and minimum value min (step S133). Athreshold value generating section 70 uses the obtained maximum valuemax and minimum value min and the interior division ratio k stored in aninterior division ratio holding section 72 to calculate threshold valueth such that min+k(maximum value−min) (step S134). A binarizingprocessing section 74 uses the threshold value th to binarize the imagesignal supplied from the image input section 66 (step S135).

Then, as the initial value of value n, “1” is set to a counter 76 (stepS136).

A dot area detection section 78 uses the binarized output from thebinarizing processing section 74 to calculate the area S_(n) of the n-threference dot 18 and supplies the calculated area S_(n) to adifferentiator 80. The differentiator 80 calculates the differencebetween the calculated dot area S_(n) and a predetermined referencevalue S_(r) stored in a buffer 82. An absolute value calculator 84obtains the absolute value of the calculated difference. A comparator 86subjects the absolute value of the difference and the minimum value ofthe difference stored in the buffer 82 to a comparison. When the value nof the counter 76 is “1”, that is, the process for the first referencedot D₁ is performed (step S137), the minimum value def_min of thedifference has not been stored in the buffer 82. Therefore, the absolutevalue of the difference calculated by the absolute value calculator 84is as it is stored as the minimum value def_min in the buffer 82 (stepS138). In this case, the count value n is, as the minimum value dotnumber n_min for specifying the reference dot 18 having the minimumvalue, stored in the buffer 82 (step S139).

Then, the value n of the counter 76 is increased (step S140), and thenwhether or not all of the printed reference dots 18 have been processedis determined (step S141). If all of the reference dots 18 have not beenprocessed, the operation returns to step S137.

When the processes for the second and following reference dots 18 areperformed, a determination is performed that the count value n is not“1” in step S137. In this case, the comparator 86 stores the absolutevalue of the difference calculated by the absolute value calculator 84in a def register (step S142). Then, whether or not the minimum valuedef_min of the difference stored in the buffer 82 is larger than theforegoing absolute value is determined by a comparison (step S143). Ifthe absolute value def of the difference stored in the def register isnot less than the minimum value def_min of the difference stored in thebuffer 82, the operation proceeds to step S140. If it is not larger thandef_min, the absolute value def stored in the def register is employedas a new minimum value def_min of the difference which is stored in thebuffer 82 (step S144). The count value n of the counter 76 is stored inthe buffer 82 as the minimum value dot number n_min (step S145). Then,the operation proceeds to step S140.

When the all of the printed reference dots 18 have been processed and adetermination has been performed in step S141 that all of the referencedots 18 have been processed, a dot number instruction section 88instructs the printing section 64 to print data with reference dotDn_(n—min) indicated by minimum value dot number n_min stored in thebuffer 82 (step S146). In a case where dots are arranged in thedescending order of the area, a structure may be employed in which allof the dots are not processed as described above. The process may becompleted at a moment updating is interrupted from minimum value def_minof the difference has been updated so as to instruct the dot number.

In response to this, the printing section 64 prints the dot code 170corresponding to the actual multimedia information on the informationrecording medium 12.

As a result, dots can stably be recorded in such a manner that the dotarea after the binarizing process has been performed is a predeterminedreference value.

A second embodiment of the information recording apparatus according tothe present invention will now be described.

In the second embodiment, when two or more types of reference dots 18having at least different area or shape are recorded on the informationrecording medium 12, recording is performed such that at least either ofthe area or the shape is different in each of predetermined steps of theminimum resolving power of the information recording apparatus.

In a case where one area shown in FIG. 74 corresponds to the minimumresolving power of the information recording apparatus, for example,reference dots 18 in the five same units may be recorded variously suchas reference dots D₂ and D₃. Therefore, a plurality of dots having areasor shapes changed with the minimum resolving power unit are recorded toselect an optimum dot.

As a result, dots can selectively be recorded with the minimum steps forthe information recording apparatus and with the optimum dot area andshape.

A third embodiment of the information recording apparatus according tothe present invention will now be described.

In the third embodiment, as shown in FIG. 75A, assuming that thedifference between the density of the dot S_(n) and that of thebackground region is G_(n), reference dots 18 having different densitydifference G_(n) are recorded on the information recording medium 12. Byusing the information reproducing system, the recorded reference dots 18are read and binarized, and then the area of each of the read referencedots 18 and a predetermined reference value are subjected to acomparison. By employing the density corresponding to the reference dot18 having the different smaller than the predetermined threshold value,the dot code 170 corresponding to the multimedia information which mustbe recorded is recorded on the information recording medium 12. In thiscase, as shown in FIG. 75B, reference dots D₁, D₂, . . . , D_(n), . . .are recorded on different information recording medium 12. As shown inFIG. 75C, if a predetermined reference value S_(r) is larger as a resultof a comparison between the area S_(n−1) of a certain reference dotD_(n−1) and the predetermined reference value S_(r), adjustment isperformed to enlarge the difference in the density, that is, thickenedto record a next reference dot D_(n). If the dot area S_(n−1) is larger,adjustment is performed to reduce the difference in the density, thatis, light to record a next reference dot D_(n). The foregoing process isrepeated to select the optimum recording density.

FIG. 76 is a block diagram showing the above-mentioned informationrecording apparatus, and FIG. 77 is an operation flow chart.

Initially, “1” is initialized to the buffer 82 as the count value n(step S151). Then, a printing density instruction section 90 instructsthe printing section 64 to print reference dot D_(n) (D₁ in this case)having the density difference of G_(n) (G₁ in this case) from thebackground region indicated by the count value n (step S152). When theprinting section 64 has printed the reference dot 18 to correspond tothis. Then, the image input section 66 picks up the image of thereference dot 18 (step S153). Then, the maximum value and minimum valuedetection section 68 obtains the maximum value max_(n) and minimum valuemin_(n) (step S154). The threshold value generating section 70 uses theobtained maximum value max_(n), the minimum value min_(n) and theinterior division ratio k held in the interior division ratio holdingsection 72 to calculated the threshold value th such thatmin+k(max_(n)−min_(n)) (step S155). The binarizing processing section 74uses the threshold value th_(n) to binarize an image signal suppliedfrom the image input section 66. Then, the dot area detection section 78obtains the dot area S_(n) (step S156). The calculated dot area S_(n) issupplied to the differentiator 80 and the buffer 82.

The differentiator 80 calculates the difference between the calculateddot area S_(n) and the predetermined reference area vale S_(r) stored inthe buffer 82. The absolute value calculator 84 obtains the absolutevalue of the calculated difference. The comparator 86 subjects theabsolute value of the difference and the threshold value ε previouslyset to the buffer 82 to a comparison (step S157). If the absolute valueof the difference is larger than the threshold value, the calculated dotarea S_(n) and the predetermined reference area value S_(r) to acomparison (step S158). If the calculated dot area S_(n) is larger, apredetermined correction density G_(d) is subtracted from the value ofthe density difference G_(n) so that density difference G_(n+1) forprinting a next reference dot 18 is calculated. Then, a result of thecalculation is stored in the buffer 82 (step S159). If the calculateddot area S_(n) is smaller than the predetermined reference area valueS_(r), the predetermined value of the correction density G_(d) is addedto the value of the density difference G_(n) so that density differenceG_(n+1) for printing the next reference dot 18 is calculated. Then, aresult of the calculation is stored in the buffer 82 (step S160). Then,the count value n of the buffer 82 is increased (step S161), and thenthe operation returns to step S152 so that the printing densityinstruction section 90 instructs the printing section 64 to print thereference dot D_(n) (D₂ in this case) having the density difference fromthe background region of G_(n) (which is G₂ in this case).

The foregoing process is repeated. When a determination has beenperformed in step S157 that the above-mentioned of the difference issmaller than the threshold value ε, the printing density instructionsection 90 instructs the printing section 64 to print the dot code 170with the dot having the density difference from the background region ofG_(n) (step S162).

To correspond to this, the printing section 64 prints the dot code 170corresponding to the actual multimedia information with the instructeddensity difference dot.

As a result, dots can stably be recorded in such a manner that the dotarea after the binarization is made to be a predetermined referencevalue.

A fourth embodiment of the information recording apparatus according tothe present invention will now be described.

The fourth embodiment is structured such that when the density isadjusted as is performed in the third embodiment, the plural referencedots 18 are not printed on a plurality of information recording mediums12. As shown in FIG. 78A, a plurality of reference dots 18 havingdifferent densities are recorded on one information recording medium 12as is performed in the first embodiment. The regions are divided toenable the dots to be included in different regions 44. As shown in FIG.78B, binarization is performed for each of the divided regions so thatthe density of the optimum dot area is selected.

FIG. 79 is a block diagram showing the above-mentioned informationrecording apparatus. FIG. 80 is an operation flow chart.

Initially, the printing section 64 prints a plurality of reference dotsG₁, G₂, . . . , G_(n), . . . having different densities (step S171).Then, the image input section 66 picks up the images of the printedreference dots 18 (step S172). The region dividing section 92 dividesthe region into n pieces in such a manner that only one dot is includedin each region (step S173). Then, “1” is, as an initial value of thevalue n, set to the counter 76 (step S174).

Then, the maximum value and minimum value detection section 68 obtainsthe maximum value max_(n) and minimum value min_(n) in the region n(step S175). The threshold value generating section 70 uses the obtainedmaximum value max_(n) and the minimum value min_(n) and the interiordivision ratio k held by the interior division ratio holding section 72to calculate the threshold value th such that min_(n)+k(max_(n)−min_(n))(step S176). The binarizing processing section 74 uses the thresholdvalue th_(n) to binarize the image signal supplied from the image inputsection 66 (step S177).

The dot area detection section 78 calculates area S_(n) by using thebinary output from the binarizing processing section 74 to calculate thearea S_(n) of the n-th reference dot 18 to supply the calculated areaS_(n) to the differentiator 80. The differentiator 80 calculates thedifference between the calculated dot area S_(n) and the predeterminedreference value S_(r) set to the buffer 82. The absolute valuecalculator 84 obtains the absolute value of the calculated difference.The comparator 86 subjects the absolute value of the difference and theminimum value of the difference stored in the buffer 82 to a comparison.When the value n of the counter 76 is “1”, that is, a process for thefirst reference dot G₁ is performed (step S137), the minimum valuedef_min of the difference has not been stored in the buffer 82.Therefore, the absolute value of the difference calculated by theabsolute value calculator 84 is, as it is, stored in the buffer 82 asthe minimum value def_min of the difference (step S138). In this case,the count value n is, as the minimum value dot number n_min forspecifying the reference dot 18 having the minimum value, stored in thebuffer 82 (step S139).

Then, the value n of the counter 76 is increased (step S140), and thenwhether or not the process of all of the printed reference dots 18 hasbeen completed is determined (step S141). If the process has not beencompleted, the operation returns to step S175.

When processes of the second and ensuing reference dots 18 areperformed, a determination is performed in step S137 that the countvalue n is not “1”. In this case, the comparator 86 stores, into the defregister, the absolute value of the difference calculated by theabsolute value calculator 84 (step S142) to determine whether or not theminimum value def_min of the difference stored in the buffer 82 islarger than the absolute value (step S143). If the absolute value def ofthe difference stored in the def register is larger than the minimumvalue def_min stored in the buffer 82, the operation proceeds to stepS140. If it is not larger than the def_min, the absolute value def ofthe difference stored in the def register is, as the minimum valuedef_min of a new difference, stored in the buffer 82 (step S144). Thecount value n of the counter 76 at this time is, as the minimum valuedot number n_min, stored in the buffer 82 (step S145). Then, theoperation proceeds to step S140.

As described above, all of the printed reference dots 18 have beenprocessed and the determination has been performed in step S141 that theprocess of all of the reference dots 18 has been completed, the densitynumber instruction section 94 instructs the printing section 64 to printdata with the density of the reference dot G_(n—)min indicated by theminimum value dot number n_min (step S178).

To correspond to this, the printing section 64 prints the dot code 170corresponding to the actual multimedia information on the informationrecording medium 12.

As a result, even if dots having different densities are recorded on thesame information recording medium 12, an optimum density can beselected.

A fifth embodiment of the information recording apparatus according tothe present invention will now be described.

The fifth embodiment is structured such that the method according to thefirst to third embodiments in which the area and the density areslightly changed to perform recording and an appropriate area anddensity are selected is not employed. As shown in FIG. 81, informationabout the foregoing factors is previously stored in the printingcondition storage table 96. Moreover, the dot area or the dot densitycorresponding to information relating to the information recordingmedium 12, such as the type of the information recording medium 12 andthe amount of exposure at the recording operation and supplied from theinput unit 98, are read from the printing condition storage table 96.Then, a printer 100 performs printing with the foregoing area or thedensity.

Thus, trial printing is not needed and recording can be performed withappropriate recording density or the data area.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form can be changed in the details ofconstruction and in the combination and arrangement of parts withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

(1) An information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   reference dot detection means which binarizes the image                signal with a predetermined threshold value prior to                generating binarized data so as to detect a reference                dot from the binarized code image;            -   dot area measuring means for measuring the area of the                reference dot detected by the reference dot detection                means;            -   threshold value modifying means for modifying the                threshold value in such a manner that the area measured                by the dot area measuring means approaches a                predetermined target value; and            -   threshold value determining means for binarizing the                image signal with the threshold value modified by the                threshold value modifying means.

Thus, a binarizing process can be performed to obtain dots of a desiredsize without dependency on expansion and contraction of the dotsattributable to the recording conditions.

Even if the dot has anisotropy or whisker type noise is superimposed onthe dot, the binarizing process, which cannot be performed in the casewhere the dot diameter is used, can effectively be performed.

(2) An information reproducing system according to (1), wherein thebinarizing means binarizes the image signal read by the reading means inone of field and frame units.

Since the threshold value of the same code image obtained by measuringthe reference dot area is modified so as to be again binarized,binarization can be performed in such a manner that the dot area canaccurately be made coincide with the target value.

(3) An information reproducing system according to (1), wherein

-   -   the code reading means successively reads the code image, and    -   the binarizing means modifies the threshold value of the        successive image signals read by the reading means in one of the        previous field and previous frame in accordance with the area of        the detected reference dot so as to binarize the one of the        present field and present frame with the modified threshold        value.

In a case where the code images are successively read over a pluralityof frames, the light quantity and the recording condition are notconsiderably changed among the continuous frames. Therefore, thethreshold value can be determined while making a reference to the valueof the previous frame. As a result, a memory for storing the images canbe omitted and a real time process can be performed.

(4) An information reproducing system according to (1), wherein thereference dot is one of a data dot and an insulated dot havingsubstantially the same size and same shape as those of the data dot.

Since a dot recorded in a state approximating the state in which thedata dot has been recorded is used as the reference dot or the referencedot is the insulated dot which does not interfere with another dot, thedata dot can reliably be allowed to approximate a target area.

(5) An information reproducing system according to (1), wherein the dotcode recorded on the information recording medium includes a data codecorresponding to multimedia information and a pattern code fordetermining the position at which the data code is read, and

the reference dot is at least a portion of the pattern code.

Since the pattern dot, which is a portion of the pattern code, is anisolated dot having the substantially the same size and the same shapeas those of the data dot and the area is measured to detect the centroidfor determining the position, use of a result enables the process to beperformed efficiently.

Since the marker, which is a portion of the pattern code, is detected inthe initial stage of the reading process and the area is measured todetect the centroid for determining the position, use of a resultenables the process to be performed efficiently.

(6) An information reproducing system according to (5), wherein

-   -   the dot area measuring means includes:        -   dot interval measuring means for measuring the distance            between predetermined dots forming the pattern code; and        -   area correction means for correcting the area of the            reference dot or the target value in accordance with the            interval between dots measured by the dot interval measuring            means.

Since change in the dot area occurring due to vertical movement of thecamera is corrected, the area can stably be measured.

Moreover, coping with change in the magnification of the optical systemcan be performed and codes (50 μm or 60 μm) printed at differentmagnifications can be read.

(7) An information reproducing system according to (1), wherein

-   -   the reference dot detection means detects a plurality of        reference dots; and    -   the dot area measuring means has average area calculating means        for calculating the average area of the detected plural        reference dots.

Since the average area of the plural reference dots is calculated, aninfluence of noise can be compensated and thus the area can becalculated more accurately.

(8) An information reproducing system according to (7), wherein

-   -   the dot area measuring means has dot selection means for        inhibiting input of the area of the reference into the average        area calculating means in a case where the measured area of each        reference dot is larger than a predetermined range.

Since the dot area calculated erroneously attributable to a stain, apatchy portion and blurring is omitted from the calculation, the averagearea can stably be calculated.

(9) An information reproducing system according to (1), wherein

-   -   the threshold value modifying means has threshold value holding        means for counting the number of reference dots detected by the        reference dot detection means, determines whether or not the        counted number of the reference dots satisfies a predetermined        number and inhibits modification of the threshold value in a        case where the counted number of reference dots is less than the        predetermined number.

If a satisfactory large number of reference dots are not detected, thethreshold value is not modified. Thus, deterioration in the reliabilityof the threshold value can be prevented.

(10) An information reproducing system according to (1), wherein

-   -   the threshold value modifying means includes;        -   peak value detection means for detecting the maximum value            and the minimum value of the luminance from a predetermined            detection region;        -   interior division ratio modifying means for modifying the            interior division ratio in accordance with the amount of            modification of the interior division ratio calculated from            the difference between the area measured by the dot area            measuring means and the predetermined target value; and        -   threshold value calculating means which divides the value            detected by the peak value detection means with the interior            division ratio modified by the interior division ratio            modifying means so as to calculate the threshold value.

As contrasted with the structure in which the threshold value isdirectly modified, the dot area does not depend upon the change in thequantity of illumination light, the threshold value for the binarizationcan stably be modified while causing the code recording condition toreflect.

(11) An information reproducing system according to (10), wherein thepeak value detection means interrupts following processes for the imagesignal for a subject frame in one of a case where detected minimum valueis larger than a predetermined first threshold value and a case wherethe detected maximum value is smaller than a predetermined secondthreshold value.

In a case where no code exists in the image or if the image of the codecannot be picked up because of insufficient quantity of illuminationlight, the following processes are interrupted. Thus, wasteful processesare omitted and the processing speed can be raised.

(12) An information reproducing system according to (10), wherein thepeak value detection means has selective average calculating means forcalculating the absolute value of the difference between pixels adjacentto a pixel of interest and for calculating the average value of theadjacent pixels only when a result of the calculation is smaller than apredetermined threshold value so that the peak values are detected fromthe average value of the calculated luminance.

If a defective pixel exists in the image pickup apparatus in the codereading means, detection of erroneous peak values can be prevented.

(13) An information reproducing system according to (10), wherein theinterior division ratio modifying means has an interior division ratiomodification amount table for determining the amount of modification ofthe interior division ratio in accordance with the relationship betweendot area S and target value S_(t) so as to determine amount Δk ofmodification of the interior division ratio from the measured dot areaand the predetermined target value in accordance with the interiordivision ratio modification amount table.

Since the table is used, calculations are not required. Moreover, onlyone operation is required to approach the optimum interior divisionratio.

(14) An information reproducing system according to (10), wherein theinterior division ratio modifying means calculates the amount Δk ofmodification of the interior division ratio by using a predeterminedcoefficient α, the dot area S and the target value S_(t) in accordancewith the following equation:ΔK=α(S_(t)−S).

Since a memory for storing a table is not required, only simplecalculations are required and thus the size of the hardware can bereduced.

(15) An information reproducing system according to (14), wherein thepredetermined coefficient α is made to be one of the same and smallerwhenever modification is repeated.

Since a large coefficient is used in the initial state of themodification, the following up characteristic can be improved. In alatter half stage in which the interior division ratios have beenconverged, a small coefficient is used. Thus, oscillation can beprevented.

(16) An information reproducing system according to (10), wherein theinterior division ratio modifying means changes the interior divisionratio in a stepped manner and provides a hysteresis characteristic.

Since the interior division ratio is changed in the stepped manner, thecalculations can be facilitated, and the size of the hardware can bereduced. Since the hysteresis characteristic is provided, changeoccurring due to noise can be restrained and binarization can stably beperformed.

(17) An information reproducing system according to (10), wherein theinterior division ratio modifying means has interior division ratiolimit means which determines whether or not the modified interiordivision ratio is in a predetermined range to clip the interior divisionratio in a case where the interior division ratio is out of thepredetermined range.

Since the interior division ratio is clipped with the predeterminedvalue, output of an abnormal interior division ratio occurring due to astain, a patchy portion and blurring can be prevented and thereforestable interior division ratio can be output.

(18) An information reproducing system according to (10), wherein

-   -   the reference dot detection means detects a plurality of        reference dots, and    -   the interior division ratio modifying means has interior        division ratio holding means for counting the number of the        detected reference dots, for determining whether or not the        counted number satisfies a predetermined number and for        inhibiting modification of the interior division ratio in a case        where the counted number does not satisfy the predetermined        number.

If a satisfactory large number of reference dots are not detected, theinterior division ratio is not modified. Thus, deterioration in thereliability of the interior division ratio can be prevented.

(19) An information reproducing system according to (10), wherein

-   -   the reading means successively reads the code images,    -   the interior division ratio modifying means modifies the        interior division ratio to one of a field and a frame which        satisfies a predetermined condition for the successive image        signals read by the reading means and holds the modified        interior division ratio for one of the following field and        frame.

Since the recording condition is not considerably changed during thereading operation in a case where the dot code images are continuouslyread, the modification of the interior division ratio with which therecording condition is corrected is completed in the first half of theframes. Thus, the following modification is inhibited so that a wastefulprocess is reduced and erroneous modification caused from noise isprevented.

(20) An information reproducing system according to (1), wherein

-   -   the dot code recorded on the information recording medium has an        attitude dot disposed in a predetermined region adjacent to the        reading start end and including information about the        information recording medium for determining the threshold value        required by the binarizing means,        -   the binarizing means includes:            -   attitude dot detection means for detecting the attitude                dot;            -   attitude reading means which binarizes the image signals                read by the reading means in one of field and frame                units so as to read information relating the information                recording medium from the attitude dot of the binarized                image detected by the attitude dot detection means; and            -   attitude storage means for storing information read by                the attitude reading means and applying information to                each of following images.

Since the attitude, such as the material of the information recordingmedium, the material of the recording material and the recording methodcan be detected prior to binarizing the code, appropriate parameter forbinarization can be provided.

(21) An information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   region dividing means for dividing the picked up screen                of the dot code into a plurality of regions;            -   characteristic amount extracting means for extracting                the characteristic amount for binarization in region                units divided by the region dividing means;            -   threshold value calculating means for calculating the                threshold value for binarization in accordance with the                characteristic amount extracted by the characteristic                amount extracting means; and            -   threshold value determining means for binarizing the                image signal with the threshold value calculated by the                threshold value calculating means.

Therefore, a consideration can be performed that the recording conditionand illumination condition are constant among regions. By extracting thecharacteristic amount for each region and by calculating the thresholdvalue, influences of shading and the like can be eliminatedsatisfactorily.

(22) An information reproducing system according to (21), wherein

-   -   the information recording medium has a reference region for        extracting the characteristic amount, and    -   the region dividing means divides the region in such a manner        that the divided region includes at least one reference region.

Since at least one reference region is included in each region, thecharacteristic amount can stably be extracted.

(23) An information reproducing system according to (22), wherein

-   -   the reference region is at least one of a marker and an        inhibition region adjacent to the marker, and    -   the characteristic amount extracting means extracts the        characteristic amount from the region.

Since the reference region is the marker or the region adjacent to themarker, the necessity of recording the reference region individuallyfrom the code can be eliminated. Thus, the recording area caneffectively be used, and the detection of the same can be facilitated.

(24) An information reproducing system according to (21), wherein thecharacteristic amount extracting means extracts the maximum value of theluminance in each of the divided regions.

The characteristic amount is made to be the maximum value of theluminance so that the reference region is made to be the ground colorportion of the information recording medium. Since the ground colorportion is widely distributed over the code, the characteristic amountcan stably be extracted even if the region is divided into relativelysmall sections. Since the state of illumination is satisfactorilyreflected on the maximum value of the luminance, the threshold value caneffectively be calculated to correspond to shading.

(25) An information reproducing system according to (21), wherein

-   -   the characteristic amount extracting means extracts the maximum        value of the luminance of each of the divided regions as a first        characteristic amount and extracts the minimum value of the        luminance of the overall screen as a second characteristic        amount, and    -   the threshold value calculating means calculates the threshold        value for each region from the maximum value and the minimum        value of the luminance in accordance with a predetermined        interior division ratio.

Since the threshold value is calculated from the maximum value and theminimum value of the luminance in accordance with the interior divisionratio, the threshold value corresponding to the amount of illuminationcan be calculated.

Since the maximum value of the luminance is extracted for each region,coping with shading can be performed. The minimum value of the luminancewhich cannot stably be extracted from each region, it can be extractedfrom the overall screen. Thus, coping with rise in the black leveloccurring due to the recording condition can be performed.

(26) An information reproducing system according to (25), wherein

-   -   the reading means continuously read the code images, and    -   the minimum value of the luminance is extracted from one of the        previous field and frame.

By using the minimum value from the previous field or frame, the presentfiled or the frame can be subjected to the binarizing process in dividedregion units.

(27) An information reproducing system according to (24) or (25),wherein the characteristic amount extract means has maximum valueaveraging means which extracts the maximum value of the luminance ineach of the divided regions and which averages the extracted maximumvalue in at least two or more adjacent fields or frames in terms oftime.

Therefore, change in the maximum value occurring due to shift of theground color of the information recording medium can be prevented.

(28) An information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   peak value detection means for detecting the maximum                value and the minimum value of the luminance from a                predetermined detection region;            -   code detection means for detecting whether or not a code                exists in the detection region;            -   minimum value replacing means for replacing the minimum                value in the detection region with the minimum value of                one of the previous field and frame in a case where the                code detection means does not detect a code; and            -   threshold value calculating means for calculating the                threshold value for binarization for the same region of                one of a next field and a next frame from the detected                maximum value and the detected or replaced minimum value                in accordance with a predetermined interior division                ratio.

If the code is out of the detection region, the minimum value (the codelevel) is made to be substantially the same as the maximum value (thebackground level) so that setting of the threshold value to thebackground level is prevented. By making a reference to the backgroundlevel, following up to change in the amount of illumination is enabled.

(29) An information reproducing system comprising:

-   -   code reading means for reading a desired dot code from an        information recording medium on which multimedia information        including at least any one of audio information, image        information and digital code data has been recorded in the form        of a dot code which can optically be read;    -   binarizing means for generating binarized data from an image        signal corresponding to the dot code read by the code reading        means; and    -   information reproducing means for restoring binarized data        generated by the binarizing means to original multimedia        information to reproduce multimedia information, wherein        -   the binarizing means includes:            -   peak value detection means for detecting the maximum                value and the minimum value of the luminance from a                predetermined detection region;            -   code detection means for detecting whether or not a code                exists in the detection region;            -   minimum value replacing means for replacing the minimum                value in the detection region with the minimum value of                the adjacent detection region in a case where the code                detection means does not detect a code; and            -   threshold value calculating means for calculating the                threshold value for binarization for the same region of                one of a next field and a next frame from the detected                maximum value and the detected or replaced minimum value                in accordance with a predetermined interior division                ratio.

If the code is out of the detection region, the minimum value (the codelevel) is made to be substantially the same as the maximum value (thebackground level) so that setting of the threshold value to thebackground level is prevented. By making a reference to the backgroundlevel, following up to change in the amount of illumination is enabled.

(30) An information reproducing system according to (28) or (29),wherein the code detection means has peak ratio determining means fordetermining whether or not the ratio of peak values detected by the peakvalue detection means is larger than a predetermined value.

By using a known peak, whether or not a code exists can reliably bedetermined with a simple process.

(31) An information recording medium for use in an informationreproducing system having code reading means for reading a desired dotcode from an information recording medium on which multimedia information including at least any one of audio information, image informationand digital code data has been recorded in the form of a dot code whichcan optically be read; binarizing means for generating binarized datafrom an image signal corresponding to the dot code read by the codereading means; and information reproducing means for restoring binarizeddata generated by the binarizing means to original multimediainformation to reproduce multimedia information, the informationrecording medium comprising:

-   -   data dots which correspond to the contents of multimedia        information and which can optically be read; and    -   a reference dot arranged to be detected by the binarizing means        and serving as a reference when the threshold value is modified        to allow the area of the detected dot to approach a        predetermined target value.

Thus, binarization to which the dot area is accurately reflected can beperformed without dependency upon expansion and contraction of dotsattributable to the recording condition.

(32) An information recording medium for use in an informationreproducing system having code reading means for reading a desired dotcode from an information recording medium on which multimediainformation including at least any one of audio information, imageinformation and digital code data has been recorded in the form of a dotcode which can optically be read; binarizing means for generatingbinarized data from an image signal corresponding to the dot code readby the code reading means; and information reproducing means forrestoring binarized data generated by the binarizing means to originalmultimedia information to reproduce multimedia information, theinformation recording medium comprising:

-   -   data dots which correspond to the contents of multimedia        information and which can optically be read; and    -   a reference dot serving as a reference when the binarizing means        detects the maximum value and the minimum value of the image        signal level corresponding to the dot code, detects a dot from a        code data binarized by a threshold value calculated from the        maximum vale and the minimum value in accordance with a        predetermined interior division ratio and modifies the interior        division ratio in such a manner that area of the detected dot        approaches a predetermined target value.

Thus, binarization to which the dot area is accurately reflected can beperformed without dependency upon expansion and contraction of dotsattributable to the recording condition and upon the state ofillumination when an image is picked up.

(33) An information recording medium according to (31) or (32), whereina plurality of the reference dots are recorded in an image pickupregion.

The plural reference dots are arranged to be detected in the imagepickup region. The binarizing means calculates the average area of theplural reference dots. Thus, the influence of noise can be eliminatedand the area can be calculated further accurately.

(34) An information recording medium according to (32), wherein theinformation recording medium has a reference region for use when thebinarizing means extracts the characteristic amount for binarization.

Since the reference region exists individually from the code, thecharacteristic amount can stably be extracted.

(35) An information recording medium according to (31) or (32), whereinthe information recording medium has dot interval measuring dots formeasuring a dot interval for correcting at least one of the area of thereference dot detected by the binarizing means and the predeterminedtarget value.

By measuring the distance between predetermined dots, the image pickupmagnification and a state of distortion can be detected. Thus, the dotarea or the target value is corrected in accordance with the detectedstates so that binarization is performed to cope with the change in themagnification and distortion.

(36) An information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   reference dot recording means for recording at least two types        of reference dots having at least different areas of shapes;    -   reference dot reading means for reading the reference dots        recorded by the reference dot recording means to binarize the        read reference dots;    -   reference dot selection means for subjecting the area of each        reference dot read by the reference dot reading means and a        predetermined reference value to a comparison to select a        reference dot having the different smaller than a predetermined        threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the reference dot        selected by the reference dot selection means.

Thus, dots can stably be recorded in such a manner that the area of thebinarized dot is made to be predetermined reference value.

(37) An information recording apparatus according to (36), wherein atleast two or more types of the reference dots are recorded in such amanner that at least one of the area and the shape is different at eachof predetermined steps of a minimum resolving power of the informationrecording apparatus.

Thus, dots can selectively be recorded with the optimum dot area andshape at the minimum steps which can be recorded by the informationrecording apparatus.

(38) An information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   reference dot recording means for recording reference dots        having different recording densities;    -   reference dot reading means for reading the reference dots        recorded by the reference dot recording means to binarize the        read reference dots;    -   recording density adjustment means for subjecting the area of        each of the reference dots read by the reference dot reading        means and a predetermined reference value to a comparison to        adjust the recording density in such a manner that the        difference is smaller than a predetermined threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the recording density        adjusted by the recording density adjustment means.

Thus, dots can stably be recorded in such a manner that the area of thebinarized dot is made to be predetermined reference value.

(39) An information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   reference dot recording means for recording at least two or more        types of reference dots having different recording densities;    -   reference dot reading means for dividing a picked up screen in        such a manner that only one reference dot recorded by the        reference dot recording means is included in a divided region        and binarizing each divided region to read the reference dot to        binarize the reference dot;    -   density selection means for subjecting the area of each        reference dot read by the reference dot reading means and a        predetermined reference value to a comparison and for selecting        the density of the reference dot having the difference smaller        than a predetermined threshold value; and    -   recording means for recording a dot code corresponding to        multimedia information in accordance with the recording density        selected by the density selection means.

Even if dots having different densities are recorded on the sameinformation recording medium, optimum density can be selected.

(40) An information recording apparatus for recording multimediainformation including at least any one of audio information, imageinformation and digital code data in the form of a dot code which canoptically be read, comprising:

-   -   input means for inputting information relating to the        information recording medium;    -   storage means for storing the relationship between information        relating to a predetermined information recording medium and one        of the area of the dot when data is recorded and the recording        density; and    -   means for reading corresponding one of the dot area and the        recording density from the storage means in accordance with        information input by the input means and relating to the        information recording medium so as to record a dot code        corresponding to multimedia information in accordance with the        one of the dot area and the recording density.

Trial printing is not required to record information with appropriaterecording density or dot area.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, and representative devices shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An information reproducing system comprising: code reading means forreading a desired dot code from an information recording medium on whichmultimedia information including at least any one of audio information,image information and digital code data has been recorded in the form ofa dot code which can optically be read, to provide an image signalcorresponding to an image formed from said dot code that has been read;binarizing means for generating binarized data from an said image signalcorresponding to the dot code read by said code reading means ; andinformation reproducing means for restoring said binarized datagenerated by said binarizing means to original the multimediainformation to reproduce and for reproducing the multimedia information,wherein said binarizing means includes: reference dot detection meanswhich binarizes the image signal with a predetermined threshold valueprior to generating binarized data so as to detect for detecting areference dot from the said binarized code image data by use of apredetermined threshold value; dot area measuring means for measuringthe an area of the reference dot detected by said reference dotdetection means; and threshold value modifying means for modifying theobtaining a modified threshold value derived in such a manner that thearea measured by said dot area measuring means approaches apredetermined target value; and , threshold value determining means forbinarizing the image signal with the threshold value modified by saidthreshold value modifying means. wherein said binarizing means generatessaid binarized data from said image signal based on said modifiedthreshold value.
 2. An information reproducing system according to claim1, wherein said binarizing means binarizes the image signal formed fromsaid dot code that has been read by said code reading means in one offield and frame units of one field or units of one frame.
 3. Aninformation reproducing system according to claim 1, wherein said codereading means successively reads the code image said dot code, and saidbinarizing means modifies the threshold value of the successive imagesignals read by said reading means in one of the previous field andprevious frame in accordance with the area of the detected reference dotso as to binarize the one of the present field and present frame withdetects, with said reference dot detection means, the reference dot frombinarized data generated from a particular image signal corresponding toan image formed from said dot code of an immediately preceding field orframe, said particular image signal having been binarized based on saidpredetermined threshold value, and wherein said binarizing means furthermeasures the area of said reference dot to obtain an area measurement,modifies the predetermined threshold value, with said threshold valuemodifying means, based on said area measurement, to derive said modifiedthreshold value, and binarizes a current field or frame based on themodified threshold value.
 4. An information reproducing system accordingto claim 1, wherein the reference dot is one of a data dot and aninsulated dot having substantially the same size and same shape as thoseof the data dot.
 5. An information reproducing system according to claim1, wherein the dot code recorded on said information recording mediumincludes a data code corresponding to the multimedia information and apattern code for determining the position at which the data code isread, and the reference dot is at least a portion of the pattern code.6. An information reproducing system according to claim 5, wherein saiddot area measuring means includes: dot interval measuring means formeasuring the distance between predetermined dots forming the patterncode; and area correction means for correcting the area of the referencedot or the target value in accordance with the interval between dotsmeasured by said dot interval measuring means.
 7. An informationreproducing system according to claim 1, wherein said reference dotdetection means detects a plurality of said reference dots; and said dotarea measuring means has average area calculating means for calculatingthe an average area from areas of the detected plural plurality of saidreference dots.
 8. An information reproducing system according to claim7, wherein said dot area measuring means has dot selection means forinhibiting input of the area of the reference dot into said average areacalculating means in a case where the measured area of each referencedot is larger than outside of a predetermined range.
 9. An informationreproducing system according to claim 1, wherein said threshold valuemodifying means has threshold value holding means for (i) counting thenumber of reference dots detected by said reference dot detection means,determines (ii) determining whether or not the counted number of thereference dots satisfies a predetermined number and inhibits (iii)inhibiting modification of the threshold value in a case where thecounted number of reference dots is less than the predetermined number.10. An information reproducing system according to claim 1, wherein saidthreshold value modifying means includes: peak value detection means fordetecting the a maximum value and the a minimum value of the a luminancefrom a predetermined detection region defined on the image formed fromthe dot code read by said code reading means; interior division ratiomodifying means for modifying the an interior division ratio inaccordance with the an amount of modification of the interior divisionratio calculated from the a difference between the area measured by saiddot area measuring means and the predetermined target value; andthreshold value calculating means which divides the value formultiplying a difference between the maximum and minimum values detectedby said peak value detection means with the interior division ratiomodified by said interior division ratio modifying means and adding theminimum value so as to calculate the obtain said modified thresholdvalue.
 11. An information reproducing system according to claim 10,wherein said peak value detection means interrupts following processesfor terminates subsequent processing of the image signal for a subjectcurrent frame in one of a case where the detected minimum value islarger than a predetermined first threshold value and a case where thedetected maximum value is smaller than a predetermined second thresholdvalue.
 12. An information reproducing system according to claim 10,wherein said peak value detection means has selective averagecalculating means for calculating the an absolute value of the adifference between luminance values of pixels that are positionedadjacent to a pixel of interest and for calculating the an average valueof the luminance values of adjacent pixels only when a result of thecalculation said absolute value is smaller than a predeterminedthreshold value so that , wherein said peak value detection meansthereby detects the peak values are detected from the calculated averagevalue of the calculated luminance values.
 13. An information reproducingsystem according to claim 10, wherein said interior division ratiomodifying means has an interior division ratio modification amount tablefor determining the an amount of modification of the interior divisionratio in accordance with the a relationship between dot area S andtarget value S_(t so as to determine and determines an) amount Δk ofmodification of the interior division ratio from the measured dot areaand the predetermined target value in accordance with said interiordivision ratio modification amount table.
 14. An information reproducingsystem according to claim 10, wherein said interior division ratiomodifying means calculates the amount Δk of modification of the interiordivision ratio by using a predetermined coefficient α, the dot area Sand the target value S_(t) in accordance with the following equation:ΔK=α(S_(t)−S).
 15. An information reproducing system according to claim14, wherein the predetermined coefficient αis made to be one of the sameand smaller whenever modification is repeated.
 16. An informationreproducing system according to claim 10, wherein said interior divisionratio modifying means changes the interior division ratio in a steppedmanner and provides allows an interior division ratio modifyingoperation to have a hysteresis characteristic.
 17. An informationreproducing system according to claim 10, wherein said interior divisionratio modifying means has interior division ratio limit means whichdetermines whether or not the modified interior division ratio is in apredetermined range to clip the interior division ratio in a case wherethe interior division ratio is out of the predetermined range.
 18. Aninformation reproducing system according to claim 10, wherein saidreference dot detection means detects a plurality of reference dots, andsaid interior division ratio modifying means has interior division ratioholding means for counting the number of the detected reference dots,for determining whether or not the counted number satisfies apredetermined number and for inhibiting modification of the interiordivision ratio in a case where the counted number does not satisfy thepredetermined number.
 19. An information reproducing system according toclaim 10, wherein said code reading means successively reads the codeimages said dot code, said interior division ratio modifying meansmodifies the interior division ratio to one of a field and a frame whichsatisfies a predetermined condition for the successive image signalsformed from said dot code read by said code reading means and holds themodified interior division ratio for one of the following field andframe.
 20. An information reproducing system according to claim 1,wherein the dot code recorded on said information recording medium hasan attitude dot disposed in a predetermined region area adjacent to thea reading start end and including information about said informationrecording medium for determining the threshold value required by saidbinarizing means, and said binarizing means includes: attitude dotdetection means for detecting the attitude dot; attitude reading meanswhich binarizes the image signals read by said reading means in one offield and frame units so as to read for reading information relatingsaid information recording medium from the attitude dot of saidbinarized image detected by said attitude dot detection means in theimage signal formed from the dot code read by said code reading meansand binarized based on the threshold value determined in accordance withsaid attitude dot; and attitude storage means for storing informationread by said attitude reading means and applying information to each offollowing images.
 21. An information recording medium for use in aninformation reproducing system having code reading means for reading adesired dot code from an information recording medium on whichmultimedia information including at least any one of audio information,image information and digital code data has been recorded in the form ofa dot code which can optically be read; binarizing means for generatingbinarized data from an image signal corresponding to the dot code readby said code reading means; and information reproducing means forrestoring binarized data generated by said binarizing means to originalmultimedia information to reproduce multimedia information, saidinformation recording medium comprising: data dots which correspond tothe contents of multimedia information and which can optically be read;and a reference dot arranged to be detected by said binarizing means andserving as a reference when the threshold value is modified to allow thearea of the detected dot to approach a predetermined target value. 22.An information recording medium according to claim 21, wherein aplurality of the reference dots are recorded in an image pickup region.23. An information recording medium according to claim 21, for use in aninformation reproducing system having code reading means for reading adot code from an information recording medium on which multimediainformation including at least any one of audio information, imageinformation and digital code data has been recorded in the form of a dotcode which can optically be read; binarizing means for generatingbinarized data, by use of a predetermined threshold value, from an imagesignal corresponding to an image of the dot code read by said codereading means; and information reproducing means for restoring thebinarized data generated by said binarizing means to the multimediainformation and for reproducing the multimedia information, saidinformation recording medium comprising: data dots which correspond tocontents of multimedia information and which can optically be read; anda reference dot arranged for use by said binarizing means when saidbinarizing means binarizes the image signal and modifies thepredetermined threshold value so that an area of the reference dot inthe image of the dot code read by said code reading means approaches apredetermined target value, said reference dot being at least part of apattern code for use in determining positions for reading the data dots;wherein said information recording medium has dot interval measuringdots for measuring a dot interval for correcting at least one of thearea of the reference dot detected by said binarizing means and thepredetermined target value.
 24. An information recording apparatus forrecording multimedia information including at least any one of audioinformation, image information and digital code data in the form of adot code which an optically be read, comprising: input means forinputting information relating to said information recording medium;storage means for storing the a predetermined relationship between theinformation relating to a predetermined the information recording mediumand one of the an area of the dot when data is recorded and the arecording density when data is recorded; and recording means for readinga corresponding one of the dot area and the recording density from saidstorage means in accordance with the information that relates to saidinformation recording medium and which has been input by said inputmeans and relating to said information recording medium so as to therebyrecord a dot code corresponding to multimedia information in accordancewith the one of the dot area and the recording density.
 25. Aninformation reproducing system according to claim 1, wherein said codereading means successively reads said dot code, and said binarizingmeans detects, with said reference dot detection means, the referencedot from binarized data generated from a particular image signalcorresponding to an image formed from said dot code of a current fieldor frame, said particular image signal having been binarized based onsaid predetermined threshold value, and wherein said binarizing meansfurther measures the area of said reference dot to obtain an areameasurement, modifies the predetermined threshold value, with saidthreshold value modifying means, based on said area measurement, toderive said modified threshold value, and binarizes the current field orframe based on the modified threshold value.